What are the advantages / disadvantes of Xen / KVM?
Can't say which is better, but KVM works very nicely. I use it to run
several Linux and Windows virtual machines that act as servers, but which
are not graphic intensive. (just basic desktop use)
Is the one that is slow the one that has 2g resident?
2 Gigs ram? Yes.
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I hope this in the right list, but I was wondering if someone could help me
with a VM I have that has lately started having problems. It had been
running for years without problems. It's possible an update is causing this,
but I can't say.
The VM is running CentOS 5.8 and after a time, the
-Original Message-
From: Robert Dinse [mailto:nan...@eskimo.com]
Sent: Sunday, May 19, 2013 10:04 PM
To: comp...@hotrodpc.com; Discussion about the virtualization on CentOS
Subject: Re: [CentOS-virt] VM Slowness
How about a top on the host? Could the virtual machine be getting swapped
how do I go about setting up
the alignment of the partitions I use?
If you use one large partition it's easy: you just create the partition
leaving 1 meg of free space before the partition. This causes the partition
to start at sector 2048, which is a number that 4096 is divisible by. Newer
I still get the following error when I try to start the VM:
redlibvirtError: internal error Process exited while reading
console log output: qemu: could not open disk image /dev/had
Is the disk image a qcow2 type file?
Someone wrote:
You should not need to do anything in virsh to dump a file
I just need a temporary pppoe server, that only uses PAP
___Can someone post a howto, just in a few lines, what to do?[...]
You have posted this at least to three groups (centos, fedora, ubuntu).
No-one here should waste time in answering your mail extensive.
Maybe he just needs a quick
The biggest issue isn't the spindown. Google 'WDTLER' and see the other,
bigger, issue. In a nutshell, TLER (Time-Limited Error Recovery; see
https://secure.wikimedia.org/wikipedia/en/wiki/TLER ) allows the drive to
not try to recover soft errors quite as long. The error recovery time can
I would like to monitor the power consumption of my server. What I am
looking for is:
How about an external device? I own one of those killawatt devices. You can
program in your local power cost, and it displays how much it actually costs
to run the server. (along with lots of other info)
I am sure if you do then you will have a mailing list on which your
fanbois can post that they want to give you money.
But this list is not for that purpose.
Once again an unnecessary personal attack.
Nonsense.
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The WD RE4-GP is a so-called ''green'' disk that's suitable for RAID
arrays. It's marketed and priced as an enterprise drive.
I've had good luck with green, 5400 rpm Samsung drives. They don't spin down
automatically and work fine in my raid 5 arrays. The cost is about $80 for
2TB drives.
I
What is the package that allows copy and paste
between windows?
How do you connect to centos? VNC?
If you're running vnc4server on the centos box, there's a program you have
to leave running named vncconfig that allows clipboard xfer...
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BTW, you can actually follow through on that:
http://www.yougotbeer.com/
Josh
That site only seems to work for people in the US. Be expensive for them to
travel here for a sixpack.
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You and your crew slowed down the internet last night with all the 5.6
downloads.
Congrats!
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After updating to 5.6 on a server this morning, I can no longer boot two
virtual machines. One is trixbox which I believe is a 32bit centos based
distro, and the other vm is a 64bit Windows 2008 installation.
The error I get in the virt-manager console is FATAL: No bootable device.
Both VMs are
A similar incident was reported during the QA. Look at the .xml file.
If it says type='raw', change it to type='qcow2' and restart libvirtd.
Would that fix the problem ?
Akemi
Thank you. After reading your message, I googled the error and found a
webpage that describes a slightly different
http://www.collegehumor.com/video/3980096/we-didnt-start-the-flame-war
The theme song of flame wars everywhere :)
Great song. At least all messages titled Centos 6 Update? Are easy to spot
and delete. :)
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What the hell is so special about CentOS 6?
indeed
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Direct comparisons between the two were difficult to judge, but the
general result was that the Host was between 2:1 and 3:1 better than the
Guest, which seems to be a rather large performance gap. Latency
differences were all over the map, which I find puzzling. The Host is
64-bit and the
Just curious, why have you stopped using LVM?
Simply for ease of maintenance: some recovery and backup utilities like
clonezilla can't work with LVM. And because the same names for volume groups
are used for each centos install, so trying to attach a drive or volume to a
new system for
I tried to install Google Chrome and received the dependencies
error. Is Centos too old for the new Chrome or is there an older
Chrome version that is compatible?
Chrome depends on a few newer packages than exist in 5.5. I'm guessing
centos 6 will have updated packages which will allow Chrome to
I'm having quite an interesting time getting up to speed with KVM/QEMU
and the various ways of creating virtual Guest VMs. But disk I/O
performance remains a bit of a question mark for me. I'm looking for
suggestions and opinions
It's possible to set up guests to use a block device that
Can so. tell me if fuse-ZFS is more trouble than it's worth?
I've tried both fuse-ZFS, and also zfs installed from rpm's on
zfsonlinux.org. Both on centos 5.5.
fuse-ZFS is more polished, but cut write speeds in half on my raid 5.
I ended up going ext4.
SME Server is great by the way - been
I have a WD RE4-GP which dropped an Adaptec 51645 RAID
controller. I ran a smartctl short test on the drive and it failed
with a read error.
What does smart say about reallocated sectors, pending sector count, drive
temperature, etc?
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KVM was a dog in testing under CentOS and RHEL 5.x. The bridged
networking has *NO* network configuration tool that understands
how to set it up, you have to do it manually, and that's a deficit I've
submitted upstream as an RFE. It may work well with CentOS and
RHEL 6, i've not had a chance to
Not just Oracle. Novell is actively pursuing Red Hat customers and
offering to support their Red Hat installations cheaper than Read Hat
does. I know a large international technology company which buys RHEL
licenses only for the first year and then switches to Novell for support
after that.
I guess this is a free service so you can stop paying Red Hat as soon as
you plan to migrate to SLES. But they expect you to migrate to SLES in the
next three years.
So this is not related to OpenSUSE.
When I said opensuse, I was referring to suse. Sorry.
The problem I have is that RHEL and
Please, folks -- These are just not CentOS issues -- and the
commercial player chess-games and interplay not even vaguely
related to the subject matter which started this thread.
Please take this elsewhere
Sorry, you're right.
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It'll be either Debian or Ubuntu from now on.
Ubuntu makes a great server. But because of recent news I tried opensuse for
the first time and I really like it.
I understand the need for stability, but for what I do, having the newest
(stable) kernel and packages has a greater benefit.
Kernel
to which news are you referring about ubuntu-wise?
I meant recent redhat news about the change in how it will deliver code to
the community. They mentioned opensuse as being a competitor, I believe.
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their changes are really aimed at oracle..the rest is smoke and
Somehow a story led me to try opensuse. Sorry, don't know which it was that
I read.
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Sorry to bring this up again. Now i am trying
the clonezilla method to downsize one of my
VM. I have created a smaller storage volume
and added to the VM. I boot up wih clonezilla
but have issue cloning the drive over. Should
I use Disk-Image or Device-Device?
To make it smaller, you
On the particular Supermicro motherboard I'm using, there is a very
long delay (10 or 15 sec) between power-on and initiation of visible
BIOS activity, so all disk drives have ample time to spin up and stabilize.
Yeah, I have used Supermicro in the past and they had the same long pause
when you
Here are some pics of the RAID configuration:
http://www.knuka.org/raid1.jpg
http://www.knuka.org/raid2.jpg
It does indeed look configured...
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Your board does not support DDR2. (url for MSI KT3 Ultra)
Support 2.5v DDR200/266/333 DDR SDRAM DIMM
The OP says this:
House-built, Gigabyte MB, AMD Phenom II X6, 6Gb RAM.
Somehow, info has gotten crossed...
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sure, if your time is worthless. you can easily burn a couple hours
recapping a motherboard, which typically exceeds the boards worth.
Amen. It's not enough to replace the bulging caps - you need to replace all
the caps of the same brand as the damaged ones. Otherwise you'll just be
doing it
Hmm, I am not sure if I understand you correctly: are you saying that
in the firmware configuration there might be an option that makes the
disks invisible for the OS?
Most controllers have a firmware you can enter at boot with a keystroke.
Once in, you create/prepare arrays or single drives,
Hmm, I am not sure if I understand you correctly: are you saying
That in the firmware configuration there might be an option that
makes the disks invisible for the OS?
No, not as such. You just have to define the arrays: sssign the drives as
needed. It's a rare thing that a factory will set up
During the next server downtime, I'll re-seat RAM
If the ram is passing memtest86+, I think reseating only serves to introduce
dust and dirt into an area where a tight connection was previously keeping
it out.
Gently press them down to make sure they're seated, sure. But pulling them
out only
How goes the repair? Got it all worked out?
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I'll re-seat the CPU, heatsink, and fan on the next downtime.
Is the CPU overheating? Pointless to reseat the cpu or even remove the
heatsink, if not.
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compdoc wrote:
I'll re-seat the CPU, heatsink, and fan on the next downtime.
Is the CPU overheating? Pointless to reseat the cpu or even remove the
heatsink, if not.
No evidence to suggest that it is.
As much as I love telling anecdotes, I have none to tell you concerning cpu
reseating
According to the man page, it apparently needs a kernel driver
named OpenIMPI, which it claims is installed in standard
distributions. I don't find it on my system.
lm_sensors is another, and I think installs ready to use from the repos.
Failing that, you should reboot and look in the
When we removed the heatsinks, the
cpus came up with them, even though
the socket lever was down in the lock position.
I've seen that in HP desktops too - the thermal paste became a hardened glue
and the cpu gets pulled right out .
Another reason to leave the heat sink on.
+36C and +39C are likely your cpu and motherboard temps. You have to look at
the temps in the cmos and match them.
The +87C is likely just a miss-reading by lm_sensors. Anything running that
hot won't be stable.
I use AMD as well, and lm_sensors tells me something is 128°C.
heh
Err, that should read 128C
-Original Message-
From: centos-boun...@centos.org [mailto:centos-boun...@centos.org] On Behalf
Of compdoc
Sent: Wednesday, March 09, 2011 4:50 PM
To: 'CentOS mailing list'
Subject: Re: [CentOS] Server hangs on CentOS 5.5
+36C and +39C are likely your cpu
1280C is about the melting point of iron. Wow!
The degree symbol was converted to text after pasting into the email and
became an '0'
It actually shows 128C in lm_sensors.
Great little program, tho.
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My centos machine is connected to my MS Windows machine on the net.
The MS Windows machine is connected to Internet via valid IP address
setting and on its secondary ip address setting it can see my centos
machine on the intranet.
Connecting any windows based computer directly to the internet is
But my question remains is there any way to instruct
yum to automatically select the right package architecture
through a setting in one of the config files rather than
having to specify which architecture you are working with
each time.
You can place an exclude statement in /etc/yum.conf
I'm running a server which is usually stable, but every
once in a while it hangs.
There can be many reasons for that. One thing I'm curious about - try
looking at the reallocated sector count, and current pending sector count
for your drives with smartctl.
The only indication that I had that there was a problem (other
that attached systems were not accessing files) was that the
fan(s) on the server were louder than normal.
Are you saying the fans were running faster than normal while it was hung?
Or are they louder than usual even while its
Windows since XP SP2 has had a perfectly decent firewall
built in and enabled by default.
Selinux is installed by default too, and usually the first thing that's
disabled when something isn't working, just as it is with windows users.
You are right about one thing: It's not 1998. It's a lot less
And I know of a major incident, the vector and targets being all
Windows systems. Sorry, I literally can't speak about how I know
or more details
I've been removing java from the computers I service. It's not used much if
at all, and it's a vector.
On one workstation I monitor, the java
If the necessary files are in trash, how do I get copy them back
to /boot properly e.g. put them in the crorrect place and how do
I know which ones are necessary?
There are several files in /boot all containing a kernel version in the
name, like:
config-2.6.18-194.17.4.el5
Besides recovering the files, you'll need to delete some of them to free up
space.
Here's an idea of how to go about it:
http://www.howtoforge.com/forums/showthread.php?t=19788
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I typically use one bridge per network card. I've never thought about
assigning all nics to one bridge, but I guess it can work if you managed it.
You typically only need one nic to connect to the wan, and one to the lan.
Eth2 can certainly have an IP address that's in the same range as your
My scepticism regarding SMART data continues ... the flaky drive
showed no errors, and a full test and full zero-write using the WD
diagnostics revealed no errors either. If the drive is bad, there's
no evidence that would cause WD to issue an RMA.
I've been having a rash of drive failures
Regarding the Marvell drivers, I had good luck with the 'sata_mv' driver
in Scientific Linux 6 just yesterday, running a pair of 4-port PCIe-x4
Tempo 'Sonnet' controller cards.
Are those the Mac/Windows Sonnet cards that go for less than $200?
What kind of performance you seeing? Are you doing
What part of KVM seems immature to you? I deploy public-facing
machines using both it and Xen, and I can't really speak to any
difference in performance or small-scall management.
I like kvm - no issues
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the hardware clock might be off by a lot when it comes back up.
If your server was set to use UTC time at install, the hardware clock will
always be wrong.
Check /etc/adjtime
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If the Marvell drivers don't pan out, it looks like I'll have
to either spend money on a 3Ware|LSI|Promise controller
The 3ware are excellent...
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yeah, definately, VM of any sort is a whole different beast, and
no way NTP should be run in a virtualized environment.
The guests I run in KVM use ntp to keep their time accurate.
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Yes, I know that I could have used KVM, VMWare
or VirtualBox, but I wanted to use what's included already.
KVM is included, you just have to select it. There is a loyal following of
Xen in the community, but I use KVM for my servers. I'm often called 'dumb'
for even talking about KVM, but I like
You need qemu-spice for using SPICE, which does not ship with RHEL5 or
RHEL6. On top of that, SPICE is only supported by Red Hat for RHEV, not
libvirt. That may change in the future, ... but when, nobody knows ;-)
Well that's certainly disappointing. Any alternatives to spice for centos? I
know
Yes, I know KVM is included, but at this stage XEN is the default and
when you use the Virtual Machine Manager, it uses XEN.
Select Server Gui only, when it's up, use yum to install everything else. I
think yum is a better way to install than the OS installer.
No, I'm not using VNC. My
On Sun, 2011-02-27 at 21:46 -0600, John R. Dennison wrote:
The machine has got to be accepted, but it is probably better
to accept it rather as one accepts a drug -- that is, grudgingly
and suspiciously. Like a drug, the machine is useful, dangerous,
and habit-forming. The oftener one
I see that there are many Realtek RTL8169S gigabit cards
going for a song on eBay.
I've always liked and used Realtek cards, and I use the RTL8169S in my
servers. However, the RTL8169S has one problem: overheating. If you buy any,
make sure they include a heatsink. Those without a heatsink are
Thanks.
I'm going to use it in Italy, so I guess heat is a problem ...
I also use the Intel nics (usually the PCI-e version) and they are a lot
more expensive, but they are an excellent card.
By the way, some of those cards on ebay show a heatsink, but don't rely on
the picture - make sure you
That just confirms my experiences. I've had issues with onboard
Realtek cards and linux. On one desktop the Realtek card would work
until the box was restarted. You would have to hard power it off and
back on for it to work again. That same box worked fine with Windows.
The old RTL8139 which is
Recently I realize the filesystem became Read-only and there is media
error message in the system log. It has passed several days without
notice.
I'm thinking of setting up a script to grep that media error and send
email.
Is there more elegant way of doing this?
This doesn't really answer
Maybe what Centos needs is a bridal registry.
Here in the US, an engaged couple can tell their friends what they'd like to
be given as wedding presents. They do this by listing items in a registry,
in various stores around town.
Anyway, the idea is, post stuff you need in a list on your site.
The problem is, the kernel seemingly randomly switches between
/dev/sdb and /dev/sdc for these devices.
I use the UUID in fstab rather than '/dev/sda', etc
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On 2/16/2011 12:41 PM, Robert Heller wrote:
The wireless on the X31 is an Intel Corporation PRO/Wireless LAN 2100
3B Mini PCI Adapter (rev 04). Intel wireless chips are *very well*
supported *out of the box* under CentOS. You do need to download
and install the proper firmware.
Isn't
However, we're not set up for UUIDs, the fstab
just shows /dev/md0, etc.
I mentioned it because I recently installed and set up servers with ubuntu
10.04 and fedora 14, while I was waiting for C6. Using the UUID is the
default now.
I also found it works fine in C5.5 - you just substitute the
end_request: I/O error, dev sda, sector 451792231
You should run: smartctl -a /dev/sda
Look for something like this line:
Reallocated_Sector_Ct 0x0033 100 100 036 Pre-fail Always - 0
If that last value is greater than 0, replace the drive...
Value is 0, on both drives.
It's still possible to have a bad sector, but not have it show up in the
Reallocated Sector Count.
What does this line say:
Current_Pending_Sector 0x0012 100 100 000 Old_age Always - 0
Is the last value greater than zero?
I notice that any VMs running under it only have access to Realtek RTL8139C
at 100 Mbps nics.
In kvm, you have the option to use e1000 or the pv drivers. You can probably
specify another nic in xen, but you'll have to research which it supports.
Just make sure you retain the mac
last value is 0, on both drives.
Looks to me like Smart thinks the drives are fine. Are they over-heating?
What drives are they? Have a model number?
Ever run memtest86+ on the system?
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undetected creeping bit errors due to lack of ECC would
be, in my book, unacceptable.
Where can one find info or studies on this sort of thing? I use non-ecc ram
in several servers, and of course most ppl use it in their desktops.
Wouldn't bit errors result in crashes or data corruption? Or
ECC allows for single bit errors to be corrected and multiple bit
errors to be noticed.
I know what it is and I've used it in the past, but I just don't see many
errors going on in desktop computers and servers that use non-ecc ram.
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Well, I can tell you how I do it. Might help.
1) create a new storage volume of the size you want with Virtual Manager.
(Host detailsStorage tab)
2) shut down the VM and add the new volume to the VM ( it now has two
virtual drives - the original and the new)
3) boot with clonezilla,
You can't add a drive temporarily and have Virtual Manager create the new
volume there? I would think even a USB stick would work...
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the best write speed I can get is about 8MB/sec
A while back I researched 4k sector drives since most new drives have them
now. There is a problem with speed if you get the partition wrong.
The answer seems to be to creating a partition with 1 meg of unpartitioned
space preceding the first
I have an Altos G510 server, (two xeon sockets) and it has a Megaraid scsi
320-0X PCI-X controller that 5.5 recognizes.
Maybe there's a chance it will do so for yours...
Good luck
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I am not sure if this is your problem but what I can determine is that
there may be a conflict with the same names of the lvm volumes; ie the old
volume that I am trying to mount has the same name as the volume on the
machine that is active.
I was wondering if you were running into that
Anyone is trying zfs in linux. Any experience can be shared
It's got some great features, but don't install the fuse-zfs version...
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I need to install a virtual machine acting as a virtual storage server
under CentOS 5.x (using kvm, xen, virtualbox or vmware).
Back when I started using virtual machines, I used guests to share large
storage.
Eventually, I found it was better to let the host do the sharing of storage,
and let
For those of you that have been using the ext4 technology preview on CentOS
5.5, how has it panned out? Does it perform as expected? How do you feel the
stability, creation of the FS and the administration of it is? Ideas and
comments welcome.
I've recently been using ext4 because I have servers
'/sbin/ifconfig -a' returns:
lo Link encap:Local Loopback
Your system is not seeing your network cards. It is only seeing your
loopback device.
I opened system-administration-network-edit-hardware device, and deleted
the mac address from the box, and pressed Probe.
Any version of Windows is stable - its only when ppl start adding the pretty
butterfly screen savers, or open email attachments that things go wrong.
It is very vulnerable, especially IE, but with a little education,
preventive steps, and decent backups, the majority of businesses in the
world
I do IT for local businesses in Denver. I build workstations and servers, do
hardware upgrades, networking, VPNs, firewalls, virtual machines - anything
a business might need. Windows and linux.
Any tech worth his salt will have learned how windows works and how to
repair it. It is possible to
I have built a new PC on which I've installed CentOS 5.5 64-bit (with
updates) which after some hours of running suddenly either hard freeze
or instant power off.
Can you check a setting in the bios - see if there's an option named: PCI
Latency Timer
I once tried moving my qcow2 VM guest files to a zfs-fuse volume, and the
VMs refused to boot after. They only ran while on ext3 or ext4.
Although I wasn't trying at that time, I understand that in order migrate
VMs between servers, you need a shared file system.
Maybe NFS is the answer?
IRQ 177 nobody cared (try booting with the irqpoll option)
report bad irq, references CPU idle
I'm assuming what is happening here is the USB controller and the add-on
E1000 controller we put in are having an old school IRQ conflict, the
question is why and how can I avoid it?
IRQ177 means
If its two servers doing the same, then I guess it's not likely they both
have the same hardware problem. The thing is, that's not something centos is
going to do on its own, so it's some program that's been added, or some
common bios setting that's wrong.
Do they connect to a UPS with a
How can I know that I have to use i386 or x86_64, my machine is not very
new though
Do some research on your computer - who makes it, what model number, what
cpu, how much ram?
i386 is 32bit, x86_64 is 64 bit. If you have 4 gigs of ram or more, you'll
likely want the 64bit.
I am in the process of configuring 2 new servers. They are running Centos
5.5 and for the last three days they have been rebooting unexpectedly, can
you point me in the right direction what to look for in the logs. I have
been checking /var/log/messages but don't see anything that hint me any
I use Fedora and Ubuntu for various photography and text applications.
Can I ask - what kind of photography applications?
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I get the same errors, but my bridges still work. I keep NetworkManager
disabled, but nm-system-settings still parses the files.
About the only difference is, I don't assign an ip addresses to the bridge,
as my VM clients only use it to access the lan to obtain their own ip
addresses.
Is
Is it the ITE IT8212 ATA RAID Controller ?
I would suspect that raid card - the few I've tried didn't work well even
with the manufacturer's supplied windows drivers. The linux drivers might
not be any better.
I'm not sure why you distrust DMA, or if it's just on this one card that you
have
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