subject:"Re\: \[CentOS\] Clustering"

On Thu, February 4, 2010 6:18 pm, Drew wrote:
 Right know we have about 30 or so linux servers scattered through out or
 district. Was looking at ways of consolidating and some sort of
 redundancy
 would be nice.

 I'm in the process of going through something like that right now. The
 solution we're pursuing is to virtualize our existing physical servers
 in virtual machines and consolidating those VM's on a smaller number
 of larger servers.

 The tools we're using allow us to keep a warm copy of a VM on
 redundant server and if we lose an entire server we're up within
 3-5min with minimal data loss. As the servers we're installing have
 VMware ESXi embedded in the server and storage is pulled from
 redundant iSCSI backends, data loss due to server failure is minimal.
 And as part of the backup process includes regular off-site backups of
 the data and VMs to another office we can, in theory, lose an entire
 building and still continue to function.


 --
 Drew


Thanks for the info. Looks like VM would be the way to go. I have been
looking at Vmware and virtualbox. Would you recommend Vmware over
virtualbox?

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Re: [CentOS] Clustering

On Thu, February 4, 2010 6:34 pm, Les Mikesell wrote:
 On 2/4/2010 3:17 PM, Bo Lynch wrote:

 Right know we have about 30 or so linux servers scattered through out or
 district. Was looking at ways of consolidating and some sort of
 redundancy
 would be nice.
 Will clustering not work with certain apps? We have a couple mysql
 dbases,
 oracle database, smb shares, nfs, email, and web servers.

 Each app has it's own best way to provide the redundancy and
 auto-failover and it's own set of tradeoffs of the added complexity vs.
 the possible reduced downtime if the primary fails.

 I'd balance the options against the low-tech method of having raid
 mirrors in swappable bays with a spare similar server chassis or two
 around plus regular backups kept at a different location.  The raid lets
 you continue in the likely event of a disk failure so you can repair it
 at a convenient time.  Other failures (motherboard, power supply) are
 less likely but can be handled by swapping the drives into an alternate
 chassis (and with Centos you'll need to re-assign the IP addresses that
 are tied to the old NIC mac addresses) with a small amount of downtime.
   And the backups cover things like operator or software errors (that
 would wipe a cluster too) or a building-level disaster that destroys the
 disks or the primary and spare chassis at the same time.  Some apps may
 be worth the effort to do better.

 --
Les Mikesell
 lesmikes...@gmail.com

Currently we are doing the low tech method. Daily and weekly backups both
onsite and off along with RAID and all that other good stuff. I was just
wondering if clustering was a better way of handling things. Thanks for
the info.
Bo

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Re: [CentOS] Clustering

On Fri, Feb 5, 2010 at 1:58 PM, Bo Lynch bly...@ameliaschools.com wrote:
 On Thu, February 4, 2010 6:18 pm, Drew wrote:
 Right know we have about 30 or so linux servers scattered through out or
 district. Was looking at ways of consolidating and some sort of
 redundancy
 would be nice.

 I'm in the process of going through something like that right now. The
 solution we're pursuing is to virtualize our existing physical servers
 in virtual machines and consolidating those VM's on a smaller number
 of larger servers.

 The tools we're using allow us to keep a warm copy of a VM on
 redundant server and if we lose an entire server we're up within
 3-5min with minimal data loss. As the servers we're installing have
 VMware ESXi embedded in the server and storage is pulled from
 redundant iSCSI backends, data loss due to server failure is minimal.
 And as part of the backup process includes regular off-site backups of
 the data and VMs to another office we can, in theory, lose an entire
 building and still continue to function.


 --
 Drew


 Thanks for the info. Looks like VM would be the way to go. I have been
 looking at Vmware and virtualbox. Would you recommend Vmware over
 virtualbox?

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AFAIK, virtualbox is desktop only virtualization while vmware has more
offering (desktop, server, cloud etc)

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Re: [CentOS] Clustering

On Fri, February 5, 2010 8:03 am, Athmane Madjoudj wrote:
 On Fri, Feb 5, 2010 at 1:58 PM, Bo Lynch bly...@ameliaschools.com wrote:
 On Thu, February 4, 2010 6:18 pm, Drew wrote:
 Right know we have about 30 or so linux servers scattered through out
 or
 district. Was looking at ways of consolidating and some sort of
 redundancy
 would be nice.

 I'm in the process of going through something like that right now. The
 solution we're pursuing is to virtualize our existing physical servers
 in virtual machines and consolidating those VM's on a smaller number
 of larger servers.

 The tools we're using allow us to keep a warm copy of a VM on
 redundant server and if we lose an entire server we're up within
 3-5min with minimal data loss. As the servers we're installing have
 VMware ESXi embedded in the server and storage is pulled from
 redundant iSCSI backends, data loss due to server failure is minimal.
 And as part of the backup process includes regular off-site backups of
 the data and VMs to another office we can, in theory, lose an entire
 building and still continue to function.


 --
 Drew


 Thanks for the info. Looks like VM would be the way to go. I have been
 looking at Vmware and virtualbox. Would you recommend Vmware over
 virtualbox?

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 AFAIK, virtualbox is desktop only virtualization while vmware has more
 offering (desktop, server, cloud etc)

 --
 Athmane Madjoudj

Whats your thoughts on Vmware server over esxi?
Really do not want to have to budget for Virtualization if I do not have to.
Thanks for any info.

Bo

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Re: [CentOS] Clustering

Bo Lynch wrote:
 

 Currently we are doing the low tech method. Daily and weekly backups both
 onsite and off along with RAID and all that other good stuff. I was just
 wondering if clustering was a better way of handling things. Thanks for
 the info.

If you are looking at VMware, ESX(i) is the nicest of the bunch but moderately 
expensive for the full version that does clustering and live moves - and you 
also need a highly reliable iscsi disk server.  But even the free version is 
very nice in terms of the management tools, low overhead, and the ability to 
overcommit the host's RAM.  You could start by building shadow copies of most 
of 
your servers that could be activated as needed, with perhaps a few being live 
with application level failover (heartbeat, drbd, database replication, etc.). 
ESXi is also a nice lab framework for testing new thing.


-- 
   Les Mikesell
lesmikes...@gmail.com

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Re: [CentOS] Clustering

Bo Lynch wrote:

 Whats your thoughts on Vmware server over esxi?
 Really do not want to have to budget for Virtualization if I do not have to.

Depends on the hardware, ideally esxi, though it is very
picky about hardware.

And you should budget for it, storage will be a big concern if
you want to provide high availability. A good small storage
array(few TB) starts at around $30-40k.

nate


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Re: [CentOS] Clustering

 Whats your thoughts on Vmware server over esxi?
 Really do not want to have to budget for Virtualization if I do not have to.
 Thanks for any info.

Here is a comparison of VMware ESXi and Server notice that server
doesn't cost money.

http://www.vmware.com/products/server/faqs.html

both are proprietary
there are a lot of good FOSS alternatives such:

KVM (require a modern hardware)
Xen (need a patched kernel: available in centos repos)
OpenVZ (need a patched kernel: available in openvz repos, mainly for
VPS but personalty i use it)

HTH

-- 
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Re: [CentOS] Clustering

 Bo Lynch wrote:


 Currently we are doing the low tech method. Daily and weekly backups
 both
 onsite and off along with RAID and all that other good stuff. I was just
 wondering if clustering was a better way of handling things. Thanks for
 the info.

 If you are looking at VMware, ESX(i) is the nicest of the bunch but
 moderately
 expensive for the full version that does clustering and live moves - and
 you
 also need a highly reliable iscsi disk server.  But even the free version
 is
 very nice in terms of the management tools, low overhead, and the ability
 to
 overcommit the host's RAM.  You could start by building shadow copies of
 most of
 your servers that could be activated as needed, with perhaps a few being
 live
 with application level failover (heartbeat, drbd, database replication,
 etc.).
 ESXi is also a nice lab framework for testing new thing.


 --
Les Mikesell
 lesmikes...@gmail.com


When you talk about the free version are your referring to Vmware server
or is there a free version of Esxi? The website is a little misleading
with free trail and such.


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Re: [CentOS] Clustering

2010-02-05 Thread Drew

 Thanks for the info. Looks like VM would be the way to go. I have been
 looking at Vmware and virtualbox. Would you recommend Vmware over
 virtualbox?

 Whats your thoughts on Vmware server over esxi?
 Really do not want to have to budget for Virtualization if I do not have to.

I know some will disagree with me but for production I recommend
sticking with VMware's ESXi product, which is free, unless you have
need of some of the more advanced features which are available through
paid options.

The downside of offerings like Virtualbox or VMware Server, where the
guest OS is hosted inside the app running on a full blown OS, is the
host itself. In my experience, the smaller footprint of VMware ESX(i)
reduces the amount of maintenance required as well as has minimal
performance impact of the guest OS's.

That said, apps like Virtualbox / WMware server do have their place.
At work I routinely create virtual machines under WMware Server to
experiment with new software before releasing it into the wild at
work. The cost overhead of running Server on my own workstation is
acceptable for testing but I wouldn't consider it for production.

-- 
Drew

Nothing in life is to be feared. It is only to be understood.
--Marie Curie
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Re: [CentOS] Clustering

Bo Lynch wrote:
 
 Whats your thoughts on Vmware server over esxi?
 Really do not want to have to budget for Virtualization if I do not have to.
 Thanks for any info.

There is a free version of ESXi - which is really the same as the paid version 
with the cluster management and vmotion functions disabled.  The only reason to 
use Server is if you need to drop it on a host that is already running things 
natively - or you need to display on the local console.  If you are starting 
from scratch, install ESXi on the hardware first and put everything on guests. 
You do need a windows box to run the control software when setting it up or 
making changes.   It can use the local server's disk for storage, but 
eventually 
you'll probably want to spend money on a reliable disk subsystem.

-- 
   Les Mikesell
lesmikes...@gmail.com

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Re: [CentOS] Clustering

2010-02-05 Thread Drew

 When you talk about the free version are your referring to Vmware server
 or is there a free version of Esxi? The website is a little misleading
 with free trail and such.

ESXi is free to use. ESX / vSphere is the paid version.



-- 
Drew

Nothing in life is to be feared. It is only to be understood.
--Marie Curie
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Re: [CentOS] Clustering

2010-02-05 Thread Les Ault

On Fri, 2010-02-05 at 07:57 -0600, Les Mikesell wrote:

 Bo Lynch wrote:
  
 
  Currently we are doing the low tech method. Daily and weekly backups both
  onsite and off along with RAID and all that other good stuff. I was just
  wondering if clustering was a better way of handling things. Thanks for
  the info.
 
 If you are looking at VMware, ESX(i) is the nicest of the bunch but 
 moderately 
 expensive for the full version that does clustering and live moves - and you 
 also need a highly reliable iscsi disk server.  But even the free version is 
 very nice in terms of the management tools, low overhead, and the ability to 
 overcommit the host's RAM.  You could start by building shadow copies of most 
 of 
 your servers that could be activated as needed, with perhaps a few being live 
 with application level failover (heartbeat, drbd, database replication, 
 etc.). 
 ESXi is also a nice lab framework for testing new thing.
 
 

There are also a lot community scripts for management as well.

http://communities.vmware.com/docs/DOC-9852


--
Les Ault VCP, RHCE
Linux Systems Administrator, Office of Information Technology
Computing Systems Services: Technical Services and Research

The University of Tennessee
135C5 Kingston Pike Building
2309 Kingston Pike
Knoxville, TN 37996
Phone: 865-974-1640

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Re: [CentOS] Clustering

Drew wrote:
 When you talk about the free version are your referring to Vmware server
 or is there a free version of Esxi? The website is a little misleading
 with free trail and such.

 ESXi is free to use. ESX / vSphere is the paid version.

A common confusion point. While there is a free license available
for ESXi and not for ESX, you can pay for ESXi to unlock additional
functionality(such as live migration, HA, DRS etc) and still keep
the thin hypervisor footprint that ESXi offers.

nate


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Re: [CentOS] Clustering

On Fri, February 5, 2010 9:02 am, Athmane Madjoudj wrote:
 Whats your thoughts on Vmware server over esxi?
 Really do not want to have to budget for Virtualization if I do not have
 to.
 Thanks for any info.

 Here is a comparison of VMware ESXi and Server notice that server
 doesn't cost money.

 http://www.vmware.com/products/server/faqs.html

 both are proprietary
 there are a lot of good FOSS alternatives such:

 KVM (require a modern hardware)
 Xen (need a patched kernel: available in centos repos)
 OpenVZ (need a patched kernel: available in openvz repos, mainly for
 VPS but personalty i use it)

 HTH

 --
 Athmane Madjoudj

Does anyone have any experience with KVM or OpenVZ? If I can stick to
something that is not proprietary that would be great. I didn't realize
there were so many options. Any info would be greatly appreciated.
Bo

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Re: [CentOS] Clustering

Bo Lynch wrote:

 
 When you talk about the free version are your referring to Vmware server
 or is there a free version of Esxi? The website is a little misleading
 with free trail and such.

You have to register, but the way it works is that you download a full-featured 
ESXi demo with a 30-day trial license and you get free license keys that you 
can 
install any time within the 30-days to downgrade it to run for an unlimited 
time 
with the clustering and cluster mangement features disabled.  You also need to 
download the vcenter control program and the image conversion tool.

And they'll send some email occasionally, but not a huge amount.


-- 
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lesmikes...@gmail.com

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Re: [CentOS] Clustering


 Does anyone have any experience with KVM or OpenVZ? If I can stick to
 something that is not proprietary that would be great. I didn't realize
 there were so many options. Any info would be greatly appreciated.
 Bo

KVM is easier (like VMware) than OpenVZ when using virt-manager to
manage virtual machine and the new version of CentOS 5.4 support KVM
(KVM is default in Fedora distro).


Personally  i use OpenVZ because my hardware doesn't support virtualization

HTH
-- 
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Re: [CentOS] Clustering

2010-02-05 Thread Rudi Ahlers


  Athmane Madjoudj

 Does anyone have any experience with KVM or OpenVZ? If I can stick to
 something that is not proprietary that would be great. I didn't realize
 there were so many options. Any info would be greatly appreciated.
 Bo

 ___


If you can, avoid OpenVZ, it's not a full virtualization platform, but
rather kernel emulation. The moment one of the VPS's has a memory hog, the
whole server will suffer.

Rather use XEN / KVM / VMWare as it gives total isolation on each VPS.

-- 
Kind Regards
Rudi Ahlers
SoftDux

Website: http://www.SoftDux.com
Technical Blog: http://Blog.SoftDux.com
Office: 087 805 9573
Cell: 082 554 7532
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Re: [CentOS] Clustering

2010-02-05 Thread Simon Billis

Bo Lynch sent a missive on 2010-02-05:

 On Fri, February 5, 2010 9:02 am, Athmane Madjoudj wrote:
 Whats your thoughts on Vmware server over esxi?
 Really do not want to have to budget for Virtualization if I do not
 have to.
 Thanks for any info.
 
 Here is a comparison of VMware ESXi and Server notice that server
 doesn't cost money.
 
 http://www.vmware.com/products/server/faqs.html
 
 both are proprietary
 there are a lot of good FOSS alternatives such:
 
 KVM (require a modern hardware)
 Xen (need a patched kernel: available in centos repos) OpenVZ (need
 a patched kernel: available in openvz repos, mainly for VPS but
 personalty i use it)
 
 HTH
 
 --
 Athmane Madjoudj
 
 Does anyone have any experience with KVM or OpenVZ? If I can stick to
 something that is not proprietary that would be great. I didn't realize
 there were so many options. Any info would be greatly appreciated. Bo

OpenVZ is containerisation and not virtualisation and therefore limits the
os running to a minor version of the base os. If you need to have say
Centos4, Centos5, Solaris 10, Windows on the same box then this is not for
you.




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Re: [CentOS] Clustering

2010-02-05 Thread m . roth

 Whats your thoughts on Vmware server over esxi?
 Really do not want to have to budget for Virtualization if I do not have
 to.
 Thanks for any info.

 Here is a comparison of VMware ESXi and Server notice that server
 doesn't cost money.

 http://www.vmware.com/products/server/faqs.html

 both are proprietary
snip
ESXi is free, but usable on one system. ESX is the full-blown version,
costs, and I *think* comes with the console... which, for some unknown
reason, is WinDoze *only*.

I believe both can be administered via browser.

mark

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Re: [CentOS] Clustering

 ESXi is free, but usable on one system. ESX is the full-blown version,
 costs, and I *think* comes with the console... which, for some unknown
 reason, is WinDoze *only*.

 I believe both can be administered via browser.

maybe because there are more windows users that Linux and / or Mac OS
X and FreeBSD.

i have read in [1] and [2] that even RedHat may do the same thing (a
Wind0w$ only console)

[1]  
http://www.internetnews.com/software/article.php/3847391/Red+Hat+Virtualization+Manager+for+Windows+Only.htm

[2] http://www.linuxtoday.com/it_management/2009110700635NWRH


I' m not sure but it will be helpful if someone confirm (or not).

Best regards.

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Re: [CentOS] Clustering

Bo Lynch wrote:
 
 
 Does anyone have any experience with KVM or OpenVZ? If I can stick to
 something that is not proprietary that would be great. I didn't realize
 there were so many options. Any info would be greatly appreciated.
 Bo

Philosophically, I don't see how running on ESXi virtualization is any more or 
less proprietary than running on IBM (Dell, etc.) hardware  directly.  Unless 
you are just being pedantic about it, the main thing to consider is whether or 
not you could move your application elsewhere easily if you had to live without 
the unique proprietary features of any platform.  And you can, if you pay 
attention to how things work.  In fact there is some standardization being done 
in the virtual containers, and I'd assume VMware is a leader in that.

-- 
   Les Mikesell
lesmikes...@gmail.com


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Re: [CentOS] Clustering

nate wrote:
 Bo Lynch wrote:
 
 Whats your thoughts on Vmware server over esxi?
 Really do not want to have to budget for Virtualization if I do not have to.
 
 Depends on the hardware, ideally esxi, though it is very
 picky about hardware.
 
 And you should budget for it, storage will be a big concern if
 you want to provide high availability. A good small storage
 array(few TB) starts at around $30-40k.

Have you investigated any of the mostly-software alternatives for this like 
openfiler, nexentastor, etc., or rolling your own iscsi server out of 
opensolaris or centos?

-- 
   Les Mikesell
lesmikes...@gmail.com
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Re: [CentOS] Clustering

On Fri, February 5, 2010 9:55 am, Les Mikesell wrote:
 Bo Lynch wrote:


 Does anyone have any experience with KVM or OpenVZ? If I can stick to
 something that is not proprietary that would be great. I didn't realize
 there were so many options. Any info would be greatly appreciated.
 Bo

 Philosophically, I don't see how running on ESXi virtualization is any
 more or
 less proprietary than running on IBM (Dell, etc.) hardware  directly.
 Unless
 you are just being pedantic about it, the main thing to consider is
 whether or
 not you could move your application elsewhere easily if you had to live
 without
 the unique proprietary features of any platform.  And you can, if you pay
 attention to how things work.  In fact there is some standardization being
 done
 in the virtual containers, and I'd assume VMware is a leader in that.

 --
Les Mikesell
 lesmikes...@gmail.com

You make a valid point. Thanks


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Re: [CentOS] Clustering

On Fri, February 5, 2010 9:57 am, Les Mikesell wrote:
 nate wrote:
 Bo Lynch wrote:

 Whats your thoughts on Vmware server over esxi?
 Really do not want to have to budget for Virtualization if I do not
 have to.

 Depends on the hardware, ideally esxi, though it is very
 picky about hardware.

 And you should budget for it, storage will be a big concern if
 you want to provide high availability. A good small storage
 array(few TB) starts at around $30-40k.

 Have you investigated any of the mostly-software alternatives for this
 like
 openfiler, nexentastor, etc., or rolling your own iscsi server out of
 opensolaris or centos?

 --
Les Mikesell
 lesmikes...@gmail.com
 ___

No I have not, but now that you mention this I will definitely look into
these. Thanks again for all your help and info. This has been a greta
discussion.
Bo Lynch


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Re: [CentOS] Clustering

Les Mikesell wrote:

 Have you investigated any of the mostly-software alternatives for this like
 openfiler, nexentastor, etc., or rolling your own iscsi server out of
 opensolaris or centos?

I have and it depends on your needs. I ran Openfiler a couple years
ago with ESX and it worked ok. The main issue there was stability. I
landed on a decent configuration that worked fine as long as you
didn't touch it(kernel updates often caused kernel panics on the
hardware which was an older HP DL580). And when Openfiler finally came
out with their newer major version the only upgrade path was to
completely re-install the OS(maybe that's changed now I don't know).

A second issue was availability, Openfiler(and others) have replication
and clustering in some cases, but I've yet to see anything come close
to what the formal commercial storage solutions can provide(seamless
fail over, online software upgrades etc). Mirrored cache is also a
big one as well.

Storage can be the biggest pain point to address when dealing with
a consolidated environment, since in many cases it remains a single
point of failure. Network fault tolerance is fairly simple to address,
and throwing more servers to take into account server failure is
easy, but the data can often only live in one place at a time. Some
higher end arrays offer synchronous replication to another system,
though that replication is not application aware(aka crash consistent)
so you are at some risk of data loss when using it with applications
that are not aggressive about data integrity(like Oracle for example).

A local vmware consulting shop here that I have a lot of respect for
says in their experience, doing crash consistent replication of
VMFS volumes between storage arrays there is about a 10% chance one
of the VMs on the volume being replicated will not be recoverable,
as a result they heavily promoted NetApp's VMware-aware replication
which is much safer. My own vendor 3PAR released similar software
a couple of weeks ago for their systems.

Shared storage can also be a significant pain point for performance
as well with a poor setup.

Another advantage to a proper enterprise-type solution is support,
mainly for firmware updates. My main array at work for example is
using Seagate enterprise SATA drives. The vendor has updated the
firmware on them twice in the past six months. So not only was the
process made easy since it was automatic, but since it's their
product they work closely with the manufacturer and are kept in the
loop when important updates/fixes come out and have access to them,
last I checked it was a very rare case to be able to get HDD firmware
updates from the manufacturer's web sites.

The system worked perfectly fine before the updates, I don't know
what the most recent update was for but the one performed in August
was around an edge case where silent data corruption could occur on
the disk if a certain type of error condition was encountered, so
the vendor sent out an urgent alert to all customers using the same
type of drive to get them updated asap.

A co-worker of mine had to update the firmware on some other Seagate
disks(SCSI) in 2008 on about 50 servers due to a performance issue
with our application, in that case he had to go to each system
individually with a DOS boot disk and update the disks, a very time
consuming process involving a lot of downtime. My company spent almost
a year trying to track down the problem before I joined and ran some
diagnostics and fairly quickly narrowed the problem down to systems
running Seagate disks(some other systems running the same app had
other brands(stupid dell), of disks that were not impacted).

A lot of firmware update tools I suspect don't work well with RAID
controllers either, since the disks are abstracted, further
complicating the issue of upgrading them.

So it all depends on what the needs are, you can go with the cheaper
software options just try to set expectations accordingly when
using them. Which for me is basically - don't freak out when it
blows up.

nate



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Re: [CentOS] Clustering

2010-02-05 Thread m . roth

 ESXi is free, but usable on one system. ESX is the full-blown version,
 costs, and I *think* comes with the console... which, for some unknown
 reason, is WinDoze *only*.

 I believe both can be administered via browser.

 maybe because there are more windows users that Linux and / or Mac OS
 X and FreeBSD.

 i have read in [1] and [2] that even RedHat may do the same thing (a
 Wind0w$ only console)
snip
Except that VMware is *based* on RHEL. Why would you *not* have a
Linux-based console?

   mark

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Re: [CentOS] Clustering

 Except that VMware is *based* on RHEL. Why would you *not* have a
 Linux-based console?

The best is to have a cross platform console because there a lot of
linux sysadmin (including me) who run linux as a primary desktop OS
-- 
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Re: [CentOS] Clustering

m.r...@5-cent.us wrote:

 Except that VMware is *based* on RHEL. Why would you *not* have a
 Linux-based console?

A common misconception. The linux based console is a VM in itself,
and is used for management purposes only, it runs on top of the
hypervisor.

nate



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Re: [CentOS] Clustering

On 2/5/2010 10:12 AM, m.r...@5-cent.us wrote:
 ESXi is free, but usable on one system. ESX is the full-blown version,
 costs, and I *think* comes with the console... which, for some unknown
 reason, is WinDoze *only*.

 I believe both can be administered via browser.

 maybe because there are more windows users that Linux and / or Mac OS
 X and FreeBSD.

 i have read in [1] and [2] that even RedHat may do the same thing (a
 Wind0w$ only console)
 snip
 Except that VMware is *based* on RHEL. Why would you *not* have a
 Linux-based console?

Esx(i) is pretty lightweight on the host side.  There's no GUI at all 
and not much you can actually do there. The vcenter client is a fairly 
complex application - probably non-trivial to port and maintain lots of 
different versions.  If you're going to lose a percentage of customers 
based on not having an appropriate platform to run the client - well you 
can do the math - they aren't dumb.

Anyway, the client doesn't need to be connected for normal operation and 
you can connect from different clients, so they don't have to be on a 
particularly reliable machine.

-- 
   Les Mikesell
 lesmikes...@gmail.com
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On Fri, Feb 5, 2010 at 7:53 AM, Athmane Madjoudj athma...@gmail.com wrote:
ESXi is free, but usable on one system. ESX is the full-blown version,
costs, and I *think* comes with the console... which, for some unknown
reason, is WinDoze *only*.

I believe both can be administered via browser.

maybe because there are more windows users that Linux and / or Mac OS
X and FreeBSD.

i have read in [1] and [2] that even RedHat may do the same thing (a
Wind0w$ only console)

[1]
http://www.internetnews.com/software/article.php/3847391/Red+Hat+Virtualization+Manager+for+Windows+Only.htm

[2] http://www.linuxtoday.com/it_management/2009110700635NWRH

I' m not sure but it will be helpful if someone confirm (or not).

Best regards.

--
Athmane Madjoudj
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It's Windows only for the management piece because it is written in
.NET, and yes it is the same for RHEV (Red Hat's Virtualization
server). I don't know why it has to be in .NET, but it is (Probably a
C# thing).

For my money, and as this is a CentOS mailing list please forgive the
following recommendations, I would go with Oracle VM...because I don't
have much money. OVM is free to download but has paid support
options. It's a really small implementation of RHEL using the Xen
kernel and has a Non-Windows management UI. It supports clustering
and high-availability with OCFS2 and does para and full
virtualization.

If I had more of a budget, I would go with RHEV. It costs a lot less
to run compared to ESX and Hyper-V, and is higher performing too.
This, of course, uses KVM and not Xen, but the performance is there.
You need RHEL 5.4 and hardware compatibility. I'm not sure if you
would be able to manage CentOS 5.4 hosts with RHEV, but it'd be worth
a try. I don't see why it wouldn't work.
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Re: [CentOS] Clustering

On 2/5/2010 10:04 AM, nate wrote:

 Have you investigated any of the mostly-software alternatives for this like
 openfiler, nexentastor, etc., or rolling your own iscsi server out of
 opensolaris or centos?

 I have and it depends on your needs. I ran Openfiler a couple years
 ago with ESX and it worked ok. The main issue there was stability. I
 landed on a decent configuration that worked fine as long as you
 didn't touch it(kernel updates often caused kernel panics on the
 hardware which was an older HP DL580). And when Openfiler finally came
 out with their newer major version the only upgrade path was to
 completely re-install the OS(maybe that's changed now I don't know).

Somewhere along the line they switch from a CentOS base to rpath for 
better package management, but I haven't followed them since.

[...]
 Another advantage to a proper enterprise-type solution is support,
 mainly for firmware updates. My main array at work for example is
 using Seagate enterprise SATA drives. The vendor has updated the
 firmware on them twice in the past six months. So not only was the
 process made easy since it was automatic, but since it's their
 product they work closely with the manufacturer and are kept in the
 loop when important updates/fixes come out and have access to them,
 last I checked it was a very rare case to be able to get HDD firmware
 updates from the manufacturer's web sites.

I had an equally frustrating experience with a Dell rebranded NetApp 
several years back.  The unit shipped with a bad moherboard FC 
controller which was a known problem and they also included an add-on 
card.  But, the guy who set it up called support where he was told that 
the problem had been fixed by this serial number and he should connect 
to the motherboard port.  The symptom was that once or twice a year it 
would see something wrong with a drive, kick it out and rebuild on a hot 
spare.  Eventually it lost several disks at once and lost the data. 
After I dug up the history I switched controllers and reinstalled 
everything from scratch and it worked after that, but by then nobody 
trusted it and it was only used for backups.   So, I no longer believe 
that paying a lot for a device that is supposed to have a good 
reputation is a sure thing - or that having a support phone number is 
going to make things better.  Everyone has different war stories, I guess...

 A co-worker of mine had to update the firmware on some other Seagate
 disks(SCSI) in 2008 on about 50 servers due to a performance issue
 with our application

Oh yeah - the drives in this device needed that too - but it wasn't that 
bad to do on one device with the NetApp software.

-- 
   Les Mikesell
lesmikes...@gmail.com
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Re: [CentOS] Clustering

2010-02-05 Thread Ross Walker

On Feb 5, 2010, at 9:03 AM, Drew drew@gmail.com wrote:

 Thanks for the info. Looks like VM would be the way to go. I have  
 been
 looking at Vmware and virtualbox. Would you recommend Vmware over
 virtualbox?

 Whats your thoughts on Vmware server over esxi?
 Really do not want to have to budget for Virtualization if I do not  
 have to.

 I know some will disagree with me but for production I recommend
 sticking with VMware's ESXi product, which is free, unless you have
 need of some of the more advanced features which are available through
 paid options.

 The downside of offerings like Virtualbox or VMware Server, where the
 guest OS is hosted inside the app running on a full blown OS, is the
 host itself. In my experience, the smaller footprint of VMware ESX(i)
 reduces the amount of maintenance required as well as has minimal
 performance impact of the guest OS's.

 That said, apps like Virtualbox / WMware server do have their place.
 At work I routinely create virtual machines under WMware Server to
 experiment with new software before releasing it into the wild at
 work. The cost overhead of running Server on my own workstation is
 acceptable for testing but I wouldn't consider it for production.

Citrix XenServer Pro is also free and it comes with live migration,  
you don't get VMotion with ESXi unless you dish out big $$ for  
Enterprise.

-Ross

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Re: [CentOS] Clustering

Les Mikesell wrote:

 Somewhere along the line they switch from a CentOS base to rpath for
 better package management, but I haven't followed them since.

Yeah the version I had at the time was based on rPath, I think
they changed to something else yet again in the past year or
so.

 trusted it and it was only used for backups.   So, I no longer believe
 that paying a lot for a device that is supposed to have a good
 reputation is a sure thing - or that having a support phone number is
 going to make things better.  Everyone has different war stories, I guess...

Oh absolutely, nothing is a sure thing, on two separate occasions
last year we had a disk failure take out an entire storage array
(I speculate that fiber errors flooded the bus and that took the
controllers off line), this was on low end crap storage. One of
our vendors OEM's low end IBM storage for some of their customers
and they reported similar events on that stuff.

In 2004 the company I was at had a *massive* outage on our EMC
array(CX600), some pretty significant data loss(~60 hours of
downtime in the first week alone), in the end it was traced
to administrator(wasn't me at the time) error. A
misconfiguration of the system allowed both controllers to go
down simultaneously. Such an error is not possible to make on
more modern systems(phew). I don't know what the specific
configuration was but the admin fessed up to it a couple years
later.

Which is why most vendors will try to push for a 2nd array and doing
some sort of replication, there's only one system in the world that
I know of that puts their money behind 100% uptime and that is the
multi million $ systems from Hitachi. They claim they've never
had to pay up for any claims.

Most other array makers don't make their systems to handle more
than 99.999% uptime on the high end. And probably 99.99% on the
mid range.

BUT under most circumstances a good storage array provides far
better availability than anything someone can build on their
own for most applications. Where good typically means the system
would be sold starting at north of $50k.

I like my own storage array because it can have up to 4 controllers
running in active-active mode(right now it has 2, getting another
2 installed in a few weeks). Recently a software update was installed
that allows the system to re-mirror itself to another controller(s)
in the system in the event of a controller failure.

Normally in a dual controller system if a controller goes down the
system goes into write-through mode to ensure data integrity which
can destroy performance, with this feature that doesn't happen,
and the system still ensures data integrity by making sure all data
is written to two locations before the write is acknowledged to
the host.

It goes well beyond that though, it automatically lays data out
so that it can survive a full shelf(up to 40 drives) failing without
skipping a beat. RAID rebuilds are very fast(up to 10x faster than
other systems), the drives are connected to a switched back plane,
there are no fiber loops on the system, every shelf of disks is
directly connected to the controllers via two fiber ports. In
the event of a power failure there is an internal disk in each
controller that the system writes it's cache out to, so no worries
about a power outage lasting longer than the batteries(typically
48-72 hours). And of course since everything is written twice,
when the power goes out you store two copies of that cache on
the internal disks, in the event one disk happens to fail
(hopefully both don't) at the precisely wrong moment.

The drives themselves are in vibration absorbing
sleds, vibration is the #1 cause of failure on disks according
to a report I read from Seagate.

http://portal.aphroland.org/~aphro/chassis-architecture.png
http://www.techopsguys.com/2009/11/20/enterprise-sata-disk-reliability/

I have had two soft failures on the system since we got it, one time
a fiber channel port had a sort of core dump, and another where
a system process crashed, both were recovered automatically without
user intervention and no noticeable impact other than the email
alerts to me.

No guarantees it won't burst into flames one day, but I do sleep
a lot better at night with this system vs the last one.

My vendor also recently introduced an interesting solution for
replication which involves 3 arrays providing synchronous long
distance replication, it works like this:

(while all arrays must be from the same vendor they do not need
to be identical in any way)

Array 1 sits in facility A
Array 2 sits in facility B (up to ~130 miles away, or 1.3ms RTT)
Array 3 sits in facility C (up to 3000 miles away, or 150ms RTT)

Array 1 is synchronously replicating to facility B (hence distance
limitations), and asynchronously replicating to facility C at
defined intervals. In the event facility A or Array 1 blows up,
Array 3 in facility C automatically connects to Array 2 and has it
send all of the data up to the point Array 1

Re: [CentOS] Clustering

2010-02-04 Thread Kwan Lowe

On Thu, Feb 4, 2010 at 3:25 PM, Bo Lynch bly...@ameliaschools.com wrote:
 Just wanted to get the lists opinion on clustering and what project to
 use. Any info would be greatly appreciated.
 Thanks

There are all types of clustering. What are you looking to do?
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Re: [CentOS] Clustering

2010-02-04 Thread Bo Lynch

On Thu, February 4, 2010 3:31 pm, Kwan Lowe wrote:
 On Thu, Feb 4, 2010 at 3:25 PM, Bo Lynch bly...@ameliaschools.com wrote:
 Just wanted to get the lists opinion on clustering and what project to
 use. Any info would be greatly appreciated.
 Thanks

 There are all types of clustering. What are you looking to do?
 ___

I guess the main objective would be availability.



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Re: [CentOS] Clustering

2010-02-04 Thread Drew

 Just wanted to get the lists opinion on clustering and what project to
 use. Any info would be greatly appreciated.
 Thanks

 There are all types of clustering. What are you looking to do?

 I guess the main objective would be availability.

We need more information then just an Availability Cluster.

What application(s) do you want to cluster? What sort of
environment/budget are you working with? What objective(s) are you
trying to achieve? What are your expectations of the cluster itself,
beyond just high availability?


-- 
Drew

Nothing in life is to be feared. It is only to be understood.
--Marie Curie
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Re: [CentOS] Clustering

2010-02-04 Thread Bo Lynch


On Thu, February 4, 2010 4:09 pm, Drew wrote:
 Just wanted to get the lists opinion on clustering and what project to
 use. Any info would be greatly appreciated.
 Thanks

 There are all types of clustering. What are you looking to do?

 I guess the main objective would be availability.

 We need more information then just an Availability Cluster.

 What application(s) do you want to cluster? What sort of
 environment/budget are you working with? What objective(s) are you
 trying to achieve? What are your expectations of the cluster itself,
 beyond just high availability?


 --
 Drew

Right know we have about 30 or so linux servers scattered through out or
district. Was looking at ways of consolidating and some sort of redundancy
would be nice.
Will clustering not work with certain apps? We have a couple mysql dbases,
oracle database, smb shares, nfs, email, and web servers.



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Re: [CentOS] Clustering

2010-02-04 Thread nate

Bo Lynch wrote:

 Right know we have about 30 or so linux servers scattered through out or
 district. Was looking at ways of consolidating and some sort of redundancy
 would be nice.
 Will clustering not work with certain apps? We have a couple mysql dbases,
 oracle database, smb shares, nfs, email, and web servers.

Maybe your looking for putting them in a virtual environment,
to cluster applications like that is fairly complex, Oracle has it's
own clustering(RAC), MySQL has clustering(with some potentially serious
limitations depending on your DB size), NFS clustering is yet another
animal, and samba clustering, well CIFS is a stateful protocol so
there really isn't a good way to do clustering there at least with
generic samba, that I'm aware of, if a server fails the clients
connected to it will lose their connection and potentially data if
they happened to be writing at the time.

In any case it sounds like clustering isn't want your looking for, I
would look towards putting the systems in VMs with HA shared storage
if you want to consolidate and provide high availability.

nate


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Re: [CentOS] Clustering

2010-02-04 Thread Drew

 Right know we have about 30 or so linux servers scattered through out or
 district. Was looking at ways of consolidating and some sort of redundancy
 would be nice.

I'm in the process of going through something like that right now. The
solution we're pursuing is to virtualize our existing physical servers
in virtual machines and consolidating those VM's on a smaller number
of larger servers.

The tools we're using allow us to keep a warm copy of a VM on
redundant server and if we lose an entire server we're up within
3-5min with minimal data loss. As the servers we're installing have
VMware ESXi embedded in the server and storage is pulled from
redundant iSCSI backends, data loss due to server failure is minimal.
And as part of the backup process includes regular off-site backups of
the data and VMs to another office we can, in theory, lose an entire
building and still continue to function.


-- 
Drew

Nothing in life is to be feared. It is only to be understood.
--Marie Curie
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Re: [CentOS] Clustering

2010-02-04 Thread Les Mikesell

On 2/4/2010 3:17 PM, Bo Lynch wrote:

 Right know we have about 30 or so linux servers scattered through out or
 district. Was looking at ways of consolidating and some sort of redundancy
 would be nice.
 Will clustering not work with certain apps? We have a couple mysql dbases,
 oracle database, smb shares, nfs, email, and web servers.

Each app has it's own best way to provide the redundancy and 
auto-failover and it's own set of tradeoffs of the added complexity vs. 
the possible reduced downtime if the primary fails.

I'd balance the options against the low-tech method of having raid 
mirrors in swappable bays with a spare similar server chassis or two 
around plus regular backups kept at a different location.  The raid lets 
you continue in the likely event of a disk failure so you can repair it 
at a convenient time.  Other failures (motherboard, power supply) are 
less likely but can be handled by swapping the drives into an alternate 
chassis (and with Centos you'll need to re-assign the IP addresses that 
are tied to the old NIC mac addresses) with a small amount of downtime. 
  And the backups cover things like operator or software errors (that 
would wipe a cluster too) or a building-level disaster that destroys the 
disks or the primary and spare chassis at the same time.  Some apps may 
be worth the effort to do better.

-- 
   Les Mikesell
lesmikes...@gmail.com
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Re: [CentOS] clustering and load balancing Apache, using nginx

2009-02-12 Thread Sergej Kandyla

Les Mikesell пишет:
 Sergej Kandyla wrote:
   
 nginx http_proxy module is universal complex solution. Also apache 
 working in prefork mode (in general cases), I don't know does 
 mod_jk\mod_proxy_ajp works in the worker-MPM mode...

 In the preforking mode apache create a child on each incoming request, 
 so it's too much expensive for resource usage.
 

 Have you actually measured this?  Preforking apache doesn't fork per 
 request, it forks enough instances to accept the concurrent connection 
 count plus a few spares.  Each child would typically handle thousands of 
 requests before exiting and requiring a new fork - the number is 
 configurable.

   
Sorry for bad explanation.
I meant that apache create a child (above MinSpareServers) for serving 
each new unique client.

I measured nginx in real life :)
On some server (~15k uniq hosts per day, ~ 100k pageviews, and with 1-3k 
concurrent tcp established connections ) with frontend(nginx) - 
backend (apache + phpfastcgi) architecture I turned off nginx proxing 
and server go away for a minute... apache forked to MaxClients (500) and 
took all memory.

Also nginx helped me protect from low-medium DDoS. When apache forked to 
maxclients, nginx could server many thousand concurrent connections. So 
I've wrote shell scripts to parse nginx logs and put IPs of bots to 
firewall table.

Therefore I find nginx (lighttpd also a good choose) enough efficient 
(at least for me). Off course you should understand what you expecting 
from nginx, what it can do and what can't.

If you want real world measurements or examples of using nginx on heavy 
loaded sites please to google. Also you could ask in the nginx at 
sysoev.ru mail list (EN).


 Also apache spend about 
 15-30Kb mem for serving each tcp connection at this time nginx only 
 1-1.5Kb. If you have, for example, abount 100 concurrent connections 
 from different IPs there is nearly 100 apache forks... it's too expensive.
 

 A freshly forked child should have nearly 100% memory shared with its 
 parent and other child instances. 
Please tell me how much resources you should have for revers proxing 
with apache for example nearly 1k-2k unique clients ?
What cpu load and memory usage will you have?

I think that apache is great software. It's very flexible and features 
rich, but it especially good as backend for dynamical applications 
(mod_php, mod_perl, etc.)
If you need to serve many thousand concurrent connections you should 
look at nginx, lighttpd, squid, etc..
IMHO.

http://www.kegel.com/c10k.html

  As things change, this will decrease, 
 but you are going to have to store the unique socket/buffer info 
 somewhere whether it is a copy-on-write fork or allocated in an 
 event-loop program.  If you run something like mod_perl, the shared 
 memory effect degrades pretty quickly because of the way perl stores 
 reference counts along with its variables, but I'd expect the base 
 apache and most module code to be pretty good about retaining their 
 inherited shared memory.

   

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Re: [CentOS] clustering and load balancing Apache, using nginx

2009-02-12 Thread Les Mikesell

Sergej Kandyla wrote:


 In the preforking mode apache create a child on each incoming request, 
 so it's too much expensive for resource usage.
 
 Have you actually measured this?  Preforking apache doesn't fork per 
 request, it forks enough instances to accept the concurrent connection 
 count plus a few spares.  Each child would typically handle thousands of 
 requests before exiting and requiring a new fork - the number is 
 configurable.

   
 Sorry for bad explanation.
 I meant that apache create a child (above MinSpareServers) for serving 
 each new unique client.

That's actually for each concurrent connection, not each unique client. 
  Browsers may fire off many simultaneous connections but http 
connections typically have a very short life, so unless users are 
downloading big files, streaming data, or have low-bandwidth connections 
(or your back end service is slow), you shouldn't have that much 
concurrency.

 I measured nginx in real life :)
 On some server (~15k uniq hosts per day, ~ 100k pageviews, and with 1-3k 
 concurrent tcp established connections ) with frontend(nginx) - 
 backend (apache + phpfastcgi) architecture I turned off nginx proxing 
 and server go away for a minute... apache forked to MaxClients (500) and 
 took all memory.

There are many factors that can affect it, but that seems like too many 
concurrent connections for that amount of traffic.  The obvious thing to 
check is whether you have keepalives on and if so, what timeout you use. 
  On a busy internet site you want it off or very short.  Also, I'm not 
sure the fastcgi interface gives the same buffer/decoupling effect that 
you get with a proxy.  With a proxy, the heavyweight backend is finished 
and can accept the next request as soon as it has sent its output to the 
proxy which may take much longer to deliver to slow clients. The fastcgi 
interface might keep the backend tied up until the output is delivered. 
   If that is the case, you would get much of the same effect with 
apache as a front end proxy.  Running apache as a proxy might work with 
less memory in threaded mode too.

 Also nginx helped me protect from low-medium DDoS. When apache forked to 
 maxclients, nginx could server many thousand concurrent connections.  So
 I've wrote shell scripts to parse nginx logs and put IPs of bots to 
 firewall table.

Basically if your backend can't deliver the data at the rate the 
requests come in you are fried anyway.

 Therefore I find nginx (lighttpd also a good choose) enough efficient 
 (at least for me). Off course you should understand what you expecting 
 from nginx, what it can do and what can't.
 
 If you want real world measurements or examples of using nginx on heavy 
 loaded sites please to google. Also you could ask in the nginx at 
 sysoev.ru mail list (EN).

Thanks, I hadn't found much about it in english.

 Also apache spend about 
 15-30Kb mem for serving each tcp connection at this time nginx only 
 1-1.5Kb. If you have, for example, abount 100 concurrent connections 
 from different IPs there is nearly 100 apache forks... it's too expensive.
 
 A freshly forked child should have nearly 100% memory shared with its 
 parent and other child instances. 
 Please tell me how much resources you should have for revers proxing 
 with apache for example nearly 1k-2k unique clients ?
 What cpu load and memory usage will you have?

I'm not sure there are good ways to measure the shared copy-on-write RAM 
of forked processes.  But 15k/connection doesn't sound unreasonable, 
keeping in mind that you have to buffer all unacknowledged data somewhere.

 I think that apache is great software. It's very flexible and features 
 rich, but it especially good as backend for dynamical applications 
 (mod_php, mod_perl, etc.)
 If you need to serve many thousand concurrent connections you should 
 look at nginx, lighttpd, squid, etc..
 IMHO.

I've been using F5 load balancers for the hard part of this for a while 
  but I'd still wonder why you have that much concurrency instead of 
delivering the page and dropping the connection.

-- 
   Les Mikesell
lesmikes...@gmail.com
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Re: [CentOS] clustering and load balancing Apache

2009-02-12 Thread Anto Marky

Thanks for your reply

On Wed, Feb 11, 2009 at 9:22 PM, J Potter jpotter-cen...@codepuppy.comwrote:


 Look at pound: http://www.apsis.ch/pound/

 If you are concerned about traffic volume, you might consider running
 squid as a transparent proxy in front of pound. I.e.:

 request - squid - pound - apache

 Where squid will return the response for everything marked as
 cacheable and still fresh; and pound will take care of load balancing
 to apache. (Pound can inspect/insert cookies to send visitors to the
 same back-end node on subsequent requests.) On some of our setups,
 squid responds to 98% of the requests coming in, and is able to
 respond to an extremely insane high volume of requests. Other list
 users might be able to provide good stats as to what sort of volume
 they can support. (I'd be curious to hear what others have seen...)

 For HA:
- 2 instances of squid, active/standby or active/active (i.e. two IP
 address in DNS for the public hostname, and have each squid instance
 pick up the others during failure).
- 2 instances of pound, active/standby
- N instances of apache

 Re: replication of content on your apache nodes, another poster
 suggested drbd. From my understanding, I do not think this is
 possible, since only one node can mount the drbd volume at a time. If
 you have shared data that needs to be seen across apache nodes, either
 stick it in SQL or mount an NFS volume across the nodes. (But then you
 have NFS in the picture, which might not be so good.)

 If your apache code is constant, then have a master apache node and
 write a shell script that runs rsync to push code changes out to the
 other instances.

 It's hard to get very specific about what's best for your setup
 without know the specifics of things like the data sync needs on the
 apache nodes, so take all of this with a grain of salt -- or as a
 default starting place.

 best,
 Jeff
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Re: [CentOS] clustering and load balancing Apache

2009-02-11 Thread Anto Marky

Hi,

Thanks for your reply,

If I have my content in a centralised system like amazon s3, will I have
problem syncronizing?


Thanks and Regards
Marky

On Tue, Feb 10, 2009 at 3:38 PM, Sergej Kandyla sk.p...@gmail.com wrote:

 Anto Marky пишет:
   Hi,
  I am new to clustering and loadbalancing in apache, What is best way
  of doing it? How do I do the clustering and what tools do I need to
  use? Do I have those tools, I use CentOS , Do i have any tools in
  CenOs which comes default in it? And how do I do apache load
  balancing? should I rely on apache forums or mailing list or is there
  any way or tool I can use in CentOS? Can any throw some vague Idea on
  how to do it so that I start reading documents before I do it?
 
 Hi,
 apache is good as backend server for dynamic applications.
 You could use something like nginx, haproxy as frontend for balancing
 multiple backend servers.
 I'm using nginx. This light web server could serve many thousand
 concurrent connections! It works great!

 look at
 http://wiki.codemongers.com/NginxLoadBalanceExample
 http://blog.kovyrin.net/2006/08/25/haproxy-load-balancer/lang/en/
 http://blog.kovyrin.net/2006/05/18/nginx-as-reverse-proxy/lang/en/
 and http://highscalability.com/


 Another issue is keeping content synchronizing between apache servers.
 There are several solutions: NAS\SAN or programbased DRBD
 http://en.wikipedia.org/wiki/DRBD.

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Re: [CentOS] clustering and load balancing Apache

2009-02-11 Thread John R Pierce

Anto Marky wrote:
 If I have my content in a centralised system like amazon s3, will I 
 have problem syncronizing?

s3 is an example of a DE-centralized distributed cloud system.

by the simple fact that you're asking such a vague and generic question, 
I'd hazard to guess, yes, you will have problems with synchronization 
whatever it is you're doing, depending on your expectations and 
experience, of course.


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Re: [CentOS] clustering and load balancing Apache

2009-02-11 Thread Rainer Duffner

John R Pierce schrieb:
 Anto Marky wrote:
   
 If I have my content in a centralised system like amazon s3, will I 
 have problem syncronizing?
 

 s3 is an example of a DE-centralized distributed cloud system.

 by the simple fact that you're asking such a vague and generic question, 
 I'd hazard to guess, yes, you will have problems with synchronization 
 whatever it is you're doing, depending on your expectations and 
 experience, of course.
   


Hm. He could try reverse-proxying his content locally ;-)




Rainer
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Re: [CentOS] clustering and load balancing Apache, using nginx

2009-02-11 Thread Sergej Kandyla

Rainer Duffner пишет:
 Sergej Kandyla schrieb:
   
 Hi,
 apache is good as backend server for dynamic applications.
 You could use something like nginx, haproxy as frontend for balancing 
 multiple backend servers.
 I'm using nginx. This light web server could serve many thousand 
 concurrent connections! It works great!

 look at
 http://wiki.codemongers.com/NginxLoadBalanceExample
 http://blog.kovyrin.net/2006/08/25/haproxy-load-balancer/lang/en/
 http://blog.kovyrin.net/2006/05/18/nginx-as-reverse-proxy/lang/en/
 and http://highscalability.com/

   
 

 Yup. NGINX is probably the fastest way to serve content nowadays.
 But content has to be static and be available as a file (AFAIK) directly
 to NGINX.
   
No, nginx could serve any kind of content via ngx_http_proxy_module 
module http://wiki.codemongers.com/NginxHttpProxyModule
For example I'm using nginx as reverse proxy for tomcat 
servers\applications.
Also I've wrote some article about using nginx in shared hosting sphere. 
Look at http://directadmin.com/forum/showthread.php?t=27344

When content located on the some server (or via NAS\SAN) nginx could 
serve this content directly using some efficient mechanisms like sendfile
http://wiki.codemongers.com/NginxHttpCoreModule#sendfile

For serving static content nginx even more times efficient than ftp!!
On some servers with low-power hardware like celeron\sempron processors 
and 512M ram I have upload rate nearly 100mbit, It's not limit for 
nginx, its a limit of sata disks and chanel to that servers :)

As for load-balancing:
http://wiki.codemongers.com/NginxHttpUpstreamModule
http://barry.wordpress.com/2008/04/28/load-balancer-update/

 There's also varnish, if you can't meet the above provision easily.


   

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Re: [CentOS] clustering and load balancing Apache

2009-02-11 Thread Sergej Kandyla

Florin Andrei пишет:
 Sergej Kandyla wrote:
   
 apache is good as backend server for dynamic applications.
 You could use something like nginx, haproxy as frontend for balancing 
 multiple backend servers.
 I'm using nginx. This light web server could serve many thousand 
 concurrent connections! It works great!
 

 In addition to the user-space solutions mentioned above, there are also 
 kernel-level solutions, such as Linux Virtual Server, or LVS:

 http://www.linuxvirtualserver.org/
   

IMHO it's not right compare light web server with Virtual servers.

Look at http://www.linuxvirtualserver.org/whatis.html
In this scheme you could naturally use nginx as loadbalancer on the Load 
Balancer Linux Box.

Also The mission of the project is to build a high-performance and 
highly available server for Linux using clustering 
http://en.wikipedia.org/wiki/Computer_cluster technology, which 
provides good scalability, reliability and serviceability.

If you need high-availability you could also use XEN\KVM or OpenVZ. 
These technologies are actively developing... XEN\KVM are supported 
natively in the RHEL\Centos kernel.
I'm prefer OpenVZ as light-weight virtualization.
http://wiki.openvz.org/HA_cluster_with_DRBD_and_Heartbeat

 I am under the impression that, speaking in general, user-space 
 balancers provide more features (are smarter), while the kernel-space 
 ones are faster (provide more in terms of raw speed and max load). I 
 could be wrong.

 Can anybody provide a performance comparison between, say, nginx and 
 LVS? (max connections, max new connections rate, max bandwidth, max 
 packets per second, etc.)

   

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Re: [CentOS] clustering and load balancing Apache, using nginx

2009-02-11 Thread Les Mikesell

Sergej Kandyla wrote:

 No, nginx could serve any kind of content via ngx_http_proxy_module 
 module http://wiki.codemongers.com/NginxHttpProxyModule
 For example I'm using nginx as reverse proxy for tomcat 
 servers\applications.

Is there some advantage to this over apache with mod_jk?

-- 
   Les Mikesell
lesmikes...@gmail.com

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Re: [CentOS] clustering and load balancing Apache, using nginx

2009-02-11 Thread Sergej Kandyla

Les Mikesell пишет:
 Sergej Kandyla wrote:
   

 No, nginx could serve any kind of content via ngx_http_proxy_module 
 module http://wiki.codemongers.com/NginxHttpProxyModule
 For example I'm using nginx as reverse proxy for tomcat 
 servers\applications.
 

 Is there some advantage to this over apache with mod_jk?

   
afaik mod_jk is only available for RHEL4\Centos4 i.e apache 2.0 (of 
course you could compile it manually for apache 2.2 coming with centos5)
So, recommended way for centos5 (apache 2.2) is using mod_proxy 
(mod_proxy_ajp)

nginx http_proxy module is universal complex solution. Also apache 
working in prefork mode (in general cases), I don't know does 
mod_jk\mod_proxy_ajp works in the worker-MPM mode...

In the preforking mode apache create a child on each incoming request, 
so it's too much expensive for resource usage. Also apache spend about 
15-30Kb mem for serving each tcp connection at this time nginx only 
1-1.5Kb. If you have, for example, abount 100 concurrent connections 
from different IPs there is nearly 100 apache forks... it's too expensive.

If you don't need full power of apache flexibility as server for dynamic 
applications, why use it for simple job such as proxing ?
So, I think nginx is great as light frontend server.

example config for proxing to tomcat backend:

location / {
rewrite ^/$ /tomcatapp/ redirect;
}

location /tomcatapp {
proxy_pass http://localhost:8080/tomcatapp;

proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

proxy_connect_timeout 120;
proxy_send_timeout 120;
proxy_read_timeout 180;

}

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Re: [CentOS] clustering and load balancing Apache

2009-02-11 Thread J Potter


Look at pound: http://www.apsis.ch/pound/

If you are concerned about traffic volume, you might consider running  
squid as a transparent proxy in front of pound. I.e.:

request - squid - pound - apache

Where squid will return the response for everything marked as  
cacheable and still fresh; and pound will take care of load balancing  
to apache. (Pound can inspect/insert cookies to send visitors to the  
same back-end node on subsequent requests.) On some of our setups,  
squid responds to 98% of the requests coming in, and is able to  
respond to an extremely insane high volume of requests. Other list  
users might be able to provide good stats as to what sort of volume  
they can support. (I'd be curious to hear what others have seen...)

For HA:
- 2 instances of squid, active/standby or active/active (i.e. two IP  
address in DNS for the public hostname, and have each squid instance  
pick up the others during failure).
- 2 instances of pound, active/standby
- N instances of apache

Re: replication of content on your apache nodes, another poster  
suggested drbd. From my understanding, I do not think this is  
possible, since only one node can mount the drbd volume at a time. If  
you have shared data that needs to be seen across apache nodes, either  
stick it in SQL or mount an NFS volume across the nodes. (But then you  
have NFS in the picture, which might not be so good.)

If your apache code is constant, then have a master apache node and  
write a shell script that runs rsync to push code changes out to the  
other instances.

It's hard to get very specific about what's best for your setup  
without know the specifics of things like the data sync needs on the  
apache nodes, so take all of this with a grain of salt -- or as a  
default starting place.

best,
Jeff
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Re: [CentOS] clustering and load balancing Apache, using nginx

2009-02-11 Thread Les Mikesell

Sergej Kandyla wrote:
 
 nginx http_proxy module is universal complex solution. Also apache 
 working in prefork mode (in general cases), I don't know does 
 mod_jk\mod_proxy_ajp works in the worker-MPM mode...
 
 In the preforking mode apache create a child on each incoming request, 
 so it's too much expensive for resource usage.

Have you actually measured this?  Preforking apache doesn't fork per 
request, it forks enough instances to accept the concurrent connection 
count plus a few spares.  Each child would typically handle thousands of 
requests before exiting and requiring a new fork - the number is 
configurable.

 Also apache spend about 
 15-30Kb mem for serving each tcp connection at this time nginx only 
 1-1.5Kb. If you have, for example, abount 100 concurrent connections 
 from different IPs there is nearly 100 apache forks... it's too expensive.

A freshly forked child should have nearly 100% memory shared with its 
parent and other child instances.  As things change, this will decrease, 
but you are going to have to store the unique socket/buffer info 
somewhere whether it is a copy-on-write fork or allocated in an 
event-loop program.  If you run something like mod_perl, the shared 
memory effect degrades pretty quickly because of the way perl stores 
reference counts along with its variables, but I'd expect the base 
apache and most module code to be pretty good about retaining their 
inherited shared memory.

 If you don't need full power of apache flexibility as server for dynamic 
 applications, why use it for simple job such as proxing ?
 So, I think nginx is great as light frontend server.

It may be, but I'd like to see some real-world  measurements.  Most of 
the discussions about more efficient approaches seem to use straw-man 
arguments that aren't realistic about the way apache works or timings of 
a few static pages under ideal conditions that don't match an internet 
web server.

-- 
   Les Mikesell
lesmikes...@gmail.com


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Re: [CentOS] clustering and load balancing Apache, using nginx

2009-02-11 Thread nate

Les Mikesell wrote:

 It may be, but I'd like to see some real-world  measurements.  Most of
 the discussions about more efficient approaches seem to use straw-man
 arguments that aren't realistic about the way apache works or timings of
 a few static pages under ideal conditions that don't match an internet
 web server.

In my experience apache has not been any kind of noticeable bottleneck.
At my last company we deployed a pair of apache reverse proxy nodes
that did:

- reverse proxy(188 rewrite rules)
- HTTP compression (compression level set to 9)
- mod_expires for some static content that we hosted on the front end
  proxy nodes
- SSL termination for the portion of the sites that needed SSL
- Header manipulation (had to remove some headers to work around
  IE browser issues with SSL)
- Serve up a maintenance page when we took the site down for
  software updates(this was on another dedicated apache instance)

traffic flow was:

internet-BigIP-proxy-BigIP-front end web servers-BigIP-back end apps
(utilizing BigIP's ability to transparently/effortlessly NAT
traffic internal to the network, and using HTTP headers to
communicate the originating IP addresses from the outside
world).

Each proxy node had 8 copies of apache going, 4 for HTTP and 4
for HTTPS, at the moment they seem to average about 125 workers
per proxy node, and an average of 80 idle workers per node.
CPU averages 3%, memory averages about 650MB(boxes have 3GB).
When I first started at the company they were trying to do this
via a low end F5 BigIP load balancer but it was not able to
provide the same level of service at low latency(and that was
when we had a dozen proxy rules). I love BigIPs but for proxies
I prefer apache. It wasn't until recently that F5 made their
code sudo multithreaded, until then even if you had a 4 CPU
load balancer, the proxy stuff could only use one of those
CPUs. Because of this limitation one large local customer F5
told me that they had to implement 5 layers of load balancers
due to their app design depended on the full proxy support in
the BigIPs to route traffic.

Systems were dual proc single core hyperthreaded. They proxied
requests for four dual proc quad core systems which seem to
average around 25-35% CPU usage and about 5GB of memory usage(8GB
total) a piece.

At the company before that we had our stuff split out per
customer, and had 3 proxy nodes in front and about 100 web servers
and application servers behind them for the biggest customers,
having 3 was just for N+1 redundancy, 1 was able to handle the
job. And those proxies were single processor.

At my current job 99% of the load is served directly by tomcat,
the application on the front end at least is simple by comparison
so there's no need for rewrite-type rules. Load balancing is
handled by F5 BigIPs, as is SSL termination. We don't do any
HTTP compression as far as I know.

I personally would not want to load balance using apache, I load
balance with BigIPs, and I do layer 7 proxying(URL inspection)
with apache. If I need to do deeper layer 7 inspection then I
may resort to F5 iRules, but the number of times I've had to
do that over the past several years I think is maybe two.
And even today with the latest version of code, our dual
processor BigIPs cannot run in multithreaded mode, it's not
supported on the platform, only on the latest  greatest(ours
is one generation back from the latest).

I use apache because I've been using it for so long and know it
so well, it's rock solid stable at least for me, and the fewer
different platforms I can use reduces complexity and improves
manageability for me.

If I was in a situation where apache couldn't scale to meet the
needs and something else was there that could handle say 5x the
load, then I might take a look. So far haven't come across that
yet.

nate

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Re: [CentOS] clustering and load balancing Apache

2009-02-11 Thread Florin Andrei

J Potter wrote:
 
 It's hard to get very specific about what's best for your setup  
 without know the specifics of things like the data sync needs on the  
 apache nodes, so take all of this with a grain of salt -- or as a  
 default starting place.

I did not ask anything related to my setup. I already use a couple 
different load balancing technologies.

I was just curious about performance comparisons between different types 
of load balancers in general.

-- 
Florin Andrei

http://florin.myip.org/
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Re: [CentOS] clustering and load balancing Apache

2009-02-11 Thread Jure Pečar

On Wed, 11 Feb 2009 11:50:34 -0800
Florin Andrei flo...@andrei.myip.org wrote:

 I was just curious about performance comparisons between different types 
 of load balancers in general.

It's hard to say ... you usualy use load balancers to achieve higher
availability and put as little as possible in the way of traffic when you
want performance (save for the most expensive hw load balancers).

For Apache, I had great success with mod_backhand, available at
www.backhand.org iirc. It's one of the smartest balancers, but only
available for apache 1.3. I've heard 1.3 is still faster than 2.x in
many cases.

But I'm nginx only now for a few years now ;)


-- 

Jure Pečar
http://jure.pecar.org
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Re: [CentOS] clustering and load balancing Apache

2009-02-10 Thread Sergej Kandyla

Anto Marky пишет:
 Hi,
 I am new to clustering and loadbalancing in apache, What is best way 
 of doing it? How do I do the clustering and what tools do I need to 
 use? Do I have those tools, I use CentOS , Do i have any tools in 
 CenOs which comes default in it? And how do I do apache load 
 balancing? should I rely on apache forums or mailing list or is there 
 any way or tool I can use in CentOS? Can any throw some vague Idea on 
 how to do it so that I start reading documents before I do it?

Hi,
apache is good as backend server for dynamic applications.
You could use something like nginx, haproxy as frontend for balancing 
multiple backend servers.
I'm using nginx. This light web server could serve many thousand 
concurrent connections! It works great!

look at
http://wiki.codemongers.com/NginxLoadBalanceExample
http://blog.kovyrin.net/2006/08/25/haproxy-load-balancer/lang/en/
http://blog.kovyrin.net/2006/05/18/nginx-as-reverse-proxy/lang/en/
and http://highscalability.com/


Another issue is keeping content synchronizing between apache servers. 
There are several solutions: NAS\SAN or programbased DRBD 
http://en.wikipedia.org/wiki/DRBD.

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Re: [CentOS] clustering and load balancing Apache

2009-02-10 Thread Rainer Duffner

Sergej Kandyla schrieb:

 Hi,
 apache is good as backend server for dynamic applications.
 You could use something like nginx, haproxy as frontend for balancing 
 multiple backend servers.
 I'm using nginx. This light web server could serve many thousand 
 concurrent connections! It works great!

 look at
 http://wiki.codemongers.com/NginxLoadBalanceExample
 http://blog.kovyrin.net/2006/08/25/haproxy-load-balancer/lang/en/
 http://blog.kovyrin.net/2006/05/18/nginx-as-reverse-proxy/lang/en/
 and http://highscalability.com/

   

Yup. NGINX is probably the fastest way to serve content nowadays.
But content has to be static and be available as a file (AFAIK) directly
to NGINX.

There's also varnish, if you can't meet the above provision easily.


 Another issue is keeping content synchronizing between apache servers. 
 There are several solutions: NAS\SAN or programbased DRBD 
 http://en.wikipedia.org/wiki/DRBD.
   

Or GFS, if one is into this sort of stuff...
But a NAS is much less complex to debug ;-)




Rainer
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Re: [CentOS] clustering and load balancing Apache

2009-02-10 Thread Florin Andrei

Sergej Kandyla wrote:
 apache is good as backend server for dynamic applications.
 You could use something like nginx, haproxy as frontend for balancing 
 multiple backend servers.
 I'm using nginx. This light web server could serve many thousand 
 concurrent connections! It works great!

In addition to the user-space solutions mentioned above, there are also 
kernel-level solutions, such as Linux Virtual Server, or LVS:

http://www.linuxvirtualserver.org/

I am under the impression that, speaking in general, user-space 
balancers provide more features (are smarter), while the kernel-space 
ones are faster (provide more in terms of raw speed and max load). I 
could be wrong.

Can anybody provide a performance comparison between, say, nginx and 
LVS? (max connections, max new connections rate, max bandwidth, max 
packets per second, etc.)

-- 
Florin Andrei

http://florin.myip.org/
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Re: [CentOS] clustering and load balancing Apache

2009-02-09 Thread Fajar Priyanto

On Tue, Feb 10, 2009 at 2:57 PM, Anto Marky markycen...@gmail.com wrote:
 Hi,
 I am new to clustering and loadbalancing in apache, What is best way of
 doing it? How do I do the clustering and what tools do I need to use? Do I
 have those tools, I use CentOS , Do i have any tools in CenOs which comes
 default in it? And how do I do apache load balancing? should I rely on
 apache forums or mailing list or is there any way or tool I can use in
 CentOS? Can any throw some vague Idea on how to do it so that I start
 reading documents before I do it?

This is a good start to give you some overview:
http://www.ibm.com/developerworks/linux/library/l-linux-ha/index.html
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Re: [CentOS] clustering and load balancing Apache

2009-02-09 Thread David Hrbáč

Fajar Priyanto napsal(a):
 
 This is a good start to give you some overview:
 http://www.ibm.com/developerworks/linux/library/l-linux-ha/index.html

Then, you can go here:
http://code.google.com/p/ath/
David Hrbáč
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Re: [CentOS] clustering and load balancing Apache

2009-02-09 Thread Anto Marky

Hi,

Thanks for the link.

On Tue, Feb 10, 2009 at 12:35 PM, Fajar Priyanto fajar...@arinet.orgwrote:

 On Tue, Feb 10, 2009 at 2:57 PM, Anto Marky markycen...@gmail.com wrote:
  Hi,
  I am new to clustering and loadbalancing in apache, What is best way of
  doing it? How do I do the clustering and what tools do I need to use? Do
 I
  have those tools, I use CentOS , Do i have any tools in CenOs which comes
  default in it? And how do I do apache load balancing? should I rely on
  apache forums or mailing list or is there any way or tool I can use in
  CentOS? Can any throw some vague Idea on how to do it so that I start
  reading documents before I do it?

 This is a good start to give you some overview:
 http://www.ibm.com/developerworks/linux/library/l-linux-ha/index.html
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Re: [CentOS] clustering and load balancing Apache

2009-02-09 Thread Anto Marky

Hi,

Thanks for the link.

On Tue, Feb 10, 2009 at 12:50 PM, David Hrbáč hrbac.c...@seznam.cz wrote:

 Fajar Priyanto napsal(a):
 
  This is a good start to give you some overview:
  http://www.ibm.com/developerworks/linux/library/l-linux-ha/index.html

 Then, you can go here:
 http://code.google.com/p/ath/
 David Hrbáč
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Re: [CentOS] clustering and load balancing Apache

2009-02-09 Thread Victor Padro

On Tue, Feb 10, 2009 at 1:21 AM, Anto Marky markycen...@gmail.com wrote:

 Hi,

 Thanks for the link.


 On Tue, Feb 10, 2009 at 12:35 PM, Fajar Priyanto fajar...@arinet.orgwrote:

 On Tue, Feb 10, 2009 at 2:57 PM, Anto Marky markycen...@gmail.com
 wrote:
  Hi,
  I am new to clustering and loadbalancing in apache, What is best way of
  doing it? How do I do the clustering and what tools do I need to use? Do
 I
  have those tools, I use CentOS , Do i have any tools in CenOs which
 comes
  default in it? And how do I do apache load balancing? should I rely on
  apache forums or mailing list or is there any way or tool I can use in
  CentOS? Can any throw some vague Idea on how to do it so that I start
  reading documents before I do it?

 This is a good start to give you some overview:
 http://www.ibm.com/developerworks/linux/library/l-linux-ha/index.html
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You should find good start up info here:
http://howtoforge.com/howtos/high-availability

Cheers,

-- 
It is human nature to think wisely and act in an absurd fashion.

Todo el desorden del mundo proviene de las profesiones mal o mediocremente
servidas
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Re: [CentOS] Clustering MySQL

2007-12-13 Thread Matt Shields

On Dec 12, 2007 4:46 PM, Karanbir Singh [EMAIL PROTECTED] wrote:
 Matt Shields wrote:
  I just got my master-master servers setup and we're running
  mysql-server-5.0.48-1.el4.centos.  I should also mention that Meetup
  presentation was given by Patrick Galbraith who used to work for MySQL
  and was responsible for adding replication to MySQL.
 

 sounds good, will you do a howto for the centos wiki ?

 - KB

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I'll see what I can do.  I'm so backlogged with work and I've promised
quite a few docs to people, but I'll try.


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Re: [CentOS] Clustering MySQL

2007-12-12 Thread Luke Dudney


On 11/12/2007 17:18, Steve Campbell wrote:
I'm just beginning to consider using the Clustering available with 
CentOS. We are going to spec out some new hardware, and after reading 
most of the Clustering manuals, I have a small question about MySQL.


I would like to run High Availability MySQL, in other words, similar 
to how you can run  HA HTTPD and the like.  The catch seems to be if I 
run MySQL on an individual server, with common MySQL replication to 
another server, how do failovers work? I see a real problem with table 
locking and the like. Is there a way to run multiple MySQL servers 
that get removed from the cluster as opposed to failing over when 
using the newer MySQL versions (I am running 3.23 now, so a little 
behind)?


Thanks for any insights.

Steve Campbell


After all the discussions regarding MySQL-style clustering (multi-master 
etc), what about a classic HA cluster for MySQL? Since the OP 
mentioned high availability, wouldn't the simplest solution be failover 
clustering (ie. single master with failover, shared storage, fenced 
nodes etc) via Centos CS?


As I haven't done this myself I can't really comment further, but does 
anyone else on the list have experience engineering a Centos Cluster 
Suit failover cluster for MySQL?


cheers
Luke

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Re: [CentOS] Clustering MySQL

2007-12-12 Thread Matt Shields

On Dec 11, 2007 12:42 PM, Karanbir Singh [EMAIL PROTECTED] wrote:
 Matt Shields wrote:
  the code).  But I saw a presentation at the Boston MySQL Meetup.com
  group about how to do master-master in mysql 5.  We're about to
  implement this in the next few weeks.  If it's done this way both

 that is imho, a mysql-5.1 only feature, where you can have rbr and
 multimaster setups that actually work. and 5.1 isnt quite ready for
 release as yet :D

 --
 Karanbir Singh : http://www.karan.org/  : [EMAIL PROTECTED]

I just got my master-master servers setup and we're running
mysql-server-5.0.48-1.el4.centos.  I should also mention that Meetup
presentation was given by Patrick Galbraith who used to work for MySQL
and was responsible for adding replication to MySQL.

-- 
-matt
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Re: [CentOS] Clustering MySQL

2007-12-12 Thread Karanbir Singh


Matt Shields wrote:

I just got my master-master servers setup and we're running
mysql-server-5.0.48-1.el4.centos.  I should also mention that Meetup
presentation was given by Patrick Galbraith who used to work for MySQL
and was responsible for adding replication to MySQL.



sounds good, will you do a howto for the centos wiki ?

- KB

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Re: [CentOS] Clustering MySQL

2007-12-11 Thread Matt Shields

On Dec 11, 2007 12:18 PM, Steve Campbell [EMAIL PROTECTED] wrote:
 I'm just beginning to consider using the Clustering available with
 CentOS. We are going to spec out some new hardware, and after reading
 most of the Clustering manuals, I have a small question about MySQL.

 I would like to run High Availability MySQL, in other words, similar to
 how you can run  HA HTTPD and the like.  The catch seems to be if I run
 MySQL on an individual server, with common MySQL replication to another
 server, how do failovers work? I see a real problem with table locking
 and the like. Is there a way to run multiple MySQL servers that get
 removed from the cluster as opposed to failing over when using the newer
 MySQL versions (I am running 3.23 now, so a little behind)?

 Thanks for any insights.

There are a number of ways to do it.  We currently have 1 master mysql
server, and multiple replicas. We then load balance the reads only
from the replicas and writes go to the master database (all handled in
the code).  But I saw a presentation at the Boston MySQL Meetup.com
group about how to do master-master in mysql 5.  We're about to
implement this in the next few weeks.  If it's done this way both
reads and writes to the db can be load balanced.  We use
linuxvirtualserver.org (heartbeat, ipvsadm and ldirectord) for load
balancing.

You might be able to contact the Meetup organizer, Sherri
http://mysql.meetup.com/137/, she usually posts the presentations
online.

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Re: [CentOS] Clustering MySQL


Matt Shields wrote:

the code).  But I saw a presentation at the Boston MySQL Meetup.com
group about how to do master-master in mysql 5.  We're about to
implement this in the next few weeks.  If it's done this way both


that is imho, a mysql-5.1 only feature, where you can have rbr and 
multimaster setups that actually work. and 5.1 isnt quite ready for 
release as yet :D


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Re: [CentOS] Clustering MySQL

2007-12-11 Thread Ryan Ordway


On Dec 11, 2007, at 9:42 AM, Karanbir Singh wrote:


Matt Shields wrote:

the code).  But I saw a presentation at the Boston MySQL Meetup.com
group about how to do master-master in mysql 5.  We're about to
implement this in the next few weeks.  If it's done this way both


that is imho, a mysql-5.1 only feature, where you can have rbr and  
multimaster setups that actually work. and 5.1 isnt quite ready for  
release as yet :D


I'm running a multi-master setup with 5.0 in production with a  
moderate amount of success. I did try 5.1 a few months ago and it died  
a horrible, fiery death.


You will definitely need auto_increment_increment and  
auto_increment_offset and replicate-same-server-id set to 0.


FYI, I recently took a MySQL High Availability class, and multi-master  
is definitely not a standard configuration. It was only briefly  
touched on, and only one other person there had it running in  
production. But, while it's not officially supported they do their  
best to make it work.


Specifically, what makes you say it is a 5.1 only feature? What does  
5.1 give you that makes it easier than 5.0?



Ryan

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Re: [CentOS] Clustering MySQL

2007-12-11 Thread J. Potter




 - master A is at position X
 - master B, replicating from A, gets to position X
 - master A syncs to its filesystem that it's at position X

 - master A receives some inserts, and is now at position Y
 - master B, replicating from A, gets to position Y
 - master A crashes before the position gets synced to filesystem
 - master A gets rebooted, recovers from innodb log, but has itself
only marked at position X
 - master B requests position Y from master A, but that position
doesn't exist yet, so replication breaks.

Perhaps someone here knows the proper recovery procedure at this  
point?


If this were master-slave, I'd probably do an LVM Snapshot and get a
fresh copy of the master db.  The same could be done for
master-master.


I'm not sure this would work, since some data will have been inserted  
in on master B as well. I.e., with master-master, a one-way sync won't  
work. The only recovery option that I can see is to destroy Master A,  
and copy Master B -- either via an LVM snapshot or shutdown, sync,  
startup -- to create a new Master A.  Maybe this is what you're  
suggesting?


Is there a better way?

best,
Jeff
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Re: [CentOS] Clustering MySQL

2007-12-11 Thread Ryan Ordway



On Dec 11, 2007, at 11:29 AM, Matt Shields wrote:

On Dec 11, 2007 1:39 PM, J. Potter [EMAIL PROTECTED]  
wrote:



...  But I saw a presentation at the Boston MySQL Meetup.com
group about how to do master-master in mysql 5.  We're about to
implement this in the next few weeks.  ...


I've run into issues with crash recovery in master-master mode:

 - master A is at position X
 - master B, replicating from A, gets to position X
 - master A syncs to its filesystem that it's at position X

 - master A receives some inserts, and is now at position Y
 - master B, replicating from A, gets to position Y
 - master A crashes before the position gets synced to filesystem
 - master A gets rebooted, recovers from innodb log, but has itself
only marked at position X
 - master B requests position Y from master A, but that position
doesn't exist yet, so replication breaks.

Perhaps someone here knows the proper recovery procedure at this  
point?


If this were master-slave, I'd probably do an LVM Snapshot and get a
fresh copy of the master db.  The same could be done for
master-master.



The problem is you'll have some inconsistency between your master A's  
view of the database and the master B's view. You lose any changes to  
the data on master B. It would be nice to be able to merge any changes  
from B that hadn't made their way to master A yet. At that point  
you're examining binlogs.


Ryan

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Re: [CentOS] Clustering MySQL

Ryan Ordway wrote:
 Specifically, what makes you say it is a 5.1 only feature? What does 5.1
 give you that makes it easier than 5.0?

specifically - rbr

we've had load of issues with mysql-5.0 recently ( i think were just
tryign to use mysql like too much of a real database, while we seem to
have clearly outgrown its capabilities :( )

issues like cascading deletes not working as yet in replicas, and quite
a few issues with stored proc's etc.

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Re: [CentOS] Clustering MySQL

2007-12-11 Thread Ryan Ordway



On Dec 11, 2007, at 2:44 PM, Karanbir Singh wrote:


Ryan Ordway wrote:
Specifically, what makes you say it is a 5.1 only feature? What  
does 5.1

give you that makes it easier than 5.0?


specifically - rbr


Ahh, true.

( i think were just tryign to use mysql like too much of a real  
database, while we seem to have clearly outgrown its capabilities :( )


I think the MySQL AB folks would object to that statement. ;-)

Ryan

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Re: [CentOS] Clustering MySQL

Matt Shields wrote:
 
 If this were master-slave, I'd probably do an LVM Snapshot and get a
 fresh copy of the master db.  The same could be done for
 master-master.
 

has a live lvm-snapshot ever worked for you as a real move-data-around
policy ? you would, at the very least, need to flush in memory data, and
have a system wide write lock in place while the snapshot is created.

its been a tempting idea, but so far of the few people I know having
tried this lvm snapshoting, have never actually managed to get it
working right for mysql dumps. So, would be good to hear from someone
who has it working.

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Re: [CentOS] Clustering MySQL

Ryan Ordway wrote:
 The problem is you'll have some inconsistency between your master A's
 view of the database and the master B's view. You lose any changes to
 the data on master B. It would be nice to be able to merge any changes
 from B that hadn't made their way to master A yet. At that point you're
 examining binlogs.

I wonder if someone has spent the time to write such a tool, that would
workout what this diff/delta was, and then be able to bring both
machines upto speed, so after a period of time ( hopefully short ), they
 would both be in the same state.

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Re: [CentOS] Clustering MySQL