Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread NightLightHosts Admin
The world needs documentation bounties.


On Thu, Jun 12, 2014 at 4:30 PM, Peter  wrote:

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> Hash: SHA1
>
> On 06/13/2014 03:47 AM, Dario Faggioli wrote:
> > If you're up for it, Xen wiki will be glad to host it! :-P
>
> I would love to do a writeup on this, but my time is extremely limited
> right now.  I'll see what I can do.
>
>
> Peter
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[CentOS-virt] Xen PV domU reported as Xen-HVM

2014-06-12 Thread Karl Johnson
Hello,

I am running two dom0s, one on CentOS 5 with Xen 4.1.2 (from Gitco) and the
other one on CentOS 6 with Xen 4.2.4 (from Xen4CentOS). I host one LVM
based domU on both from the same template (CentOS 6 PV) with the same Xen
config (see below). However, the domU on Xen 4.1 reports itself as Xen PV
while the domU on Xen4CentOS reports itself as Xen HVM.


== First domU ==

virt-what and cPanel scripts report domU as: xenpv

dom0: 2.6.18-371.6.1.el5xen Xen 4.1.2

domU Config:

bootloader = '/usr/bin/pygrub'
extra  = ''
memory = 6144
hostname   = 'web2.x.ca'
cpu_weight = 256
name   = 'vm115'
vif= ['ip=205.X.X.X, vifname=vifvm115.0, mac=00:16:3e:7a:X:X']
vnc= 0
vcpus  = 6
vncviewer  = 0
serial = 'pty'
disk   = ['phy:/dev/xen/vm115_img,xvda1,w',
'phy:/dev/xen/vm115_swap,xvda2,w']

domU kernel: 2.6.32-431.5.1.el6.x86_64

root@web2 [~]# virt-what
xen
root@web2 [~]#



== Second domU ==

virt-what and cPanel scripts report domU as: xenhvm

dom0: 3.10.32-11.el6.centos.alt.x86_64  Xen 4.2.4-29.el6

domU Config:

bootloader = '/usr/bin/pygrub'
extra  = ''
memory = 6144
hostname   = 'web3.x.ca'
cpu_weight = 256
name   = 'vm116'
vif= ['ip=205.X.X.X, vifname=vifvm116.0, mac=00:16:3e:cf:X:X']
vnc= 0
vcpus  = 6
vncviewer  = 0
serial = 'pty'
disk   = ['phy:/dev/xen/vm116_img,xvda1,w',
'phy:/dev/xen/vm116_swap,xvda2,w']

domU kernel: 2.6.32-431.5.1.el6.x86_64

root@web3 [~]# virt-what
xen
xen-hvm
root@web3 [~]#

Any idea why?

Kinds regards,

Karl
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Peter
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On 06/13/2014 08:30 AM, Peter wrote:
> On 06/13/2014 03:47 AM, Dario Faggioli wrote:
>> If you're up for it, Xen wiki will be glad to host it! :-P
> 
> I would love to do a writeup on this, but my time is extremely
> limited right now.  I'll see what I can do.

Actually, what I'll probably do is wait for CentOS 7 to drop and then
do a writeup based on that.  I'll be wanting to set up a VM from it
anyways and so then I'll kill two birds with one stone.


Peter
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Peter
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On 06/13/2014 03:47 AM, Dario Faggioli wrote:
> If you're up for it, Xen wiki will be glad to host it! :-P

I would love to do a writeup on this, but my time is extremely limited
right now.  I'll see what I can do.


Peter
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Re: [CentOS-virt] Are xen and centos incompatible?

2014-06-12 Thread Konrad Rzeszutek Wilk
> Hm, xen kinda makes the cpus and their power management invisible, too:
> 
> 
> root@heimdall:~# xenpm get-cpufreq-para
> [CPU0] failed to get cpufreq parameter
> [...]
> root@heimdall:~# xenpm  get-cpufreq-states
> root@heimdall:~# 
> 
> 
> So I guess it could as well make it so that lspci doesn't show
> passed-out devices.

I am wondering if you are using an older kernel. The xen-acpi-processor
driver should be loaded which would give the C and P states to the
hypervisor. Which in turn would result in those above commands
providing the right data.

> 
> BTW, getting some info in dmesg might be nice, like a message saying
> "xen-pciback: device 06:00.0 can be passed through to guests".  We could

You just need to boot with 'debug'  - and it should tell you that
a device is being assigned to another guest (when assigning). Also
at bootup it will tell you that it is seizinging.

Just do 'dmesg | grep pciback' and you will get it.

> actually see right away if it did work or not.  That a device disappears
> isn't too great as indication, especially not when lspci still lists it.
> 
> Of course, you could use the command (which I don't remember) to show
> devices that can be passed through.  But that may just work as well as

Such as xl or xm pci-list-assignable?

> 'xenpm get-cpufreq-states':  Apparently, there aren't any CPUs ...

See if xen-acpi-processor is loaded or built in.
> 
> 
> -- 
> Knowledge is volatile and fluid.  Software is power.
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread SilverTip257
On Thu, Jun 12, 2014 at 11:47 AM, Dario Faggioli  wrote:

> On gio, 2014-06-12 at 22:34 +1200, Peter wrote:
> > This is not a complete list of the ways you can install a VM either.  My
> > personal preference is to manually create the filesystem for the VM and
> > then install the OS core with yum.  Then after tweaking some config
> > files you can start up the VM and finish installing whatever else you
> > want with yum as well.
> >
> > While I don't think that this should be the recommended install method
> > it might be worth mentioning and even giving a wiki page with some
> > instructions on how to do it this way.  Doing an install like this is
> > actually very good for a newbie because you "get your hands dirty" and
> > get a really good understanding of how yum works and the internals of
> > the distro.
>

@Peter,
Would you mind sharing the process?
(on the CentOS or Xen wikis OR share a link to a write-up online?)

This piques my curiosity and I'd like to know more. ;-)
Thanks!


>  >
> Indeed it does!
>
> If you're up for it, Xen wiki will be glad to host it! :-P
>
> We've got both CentOS and Fedora categories on the Wiki, both hosting
> various pages, guides, instructions, etc., but none of them (I think)
> goes through the procedure you mentioned:
>
> http://wiki.xen.org/wiki/Category:CentOS
> http://wiki.xen.org/wiki/Category:Fedora
>
> Feel free to add it! :-)
>

+1 :-D


>
> Regards,
> Dario
>
> --
> <> (Raistlin Majere)
> -
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> Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
>
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Ed Heron
On Tue, 2014-06-10 at 17:21 +0100, Lars Kurth wrote:
> Hi all,
> 
> following the discussion on about documentation, I was wondering whether 
> we need to look at a standard way in which we recommend how to provision 
> images for VMs. Am starting this with a Xen hat, but the discussion 
> should not be specific to this. There are a number of options, but all 
> have some trade-offs
> 
> == #1 virt-install ==
> 
> Advantages: similar to KVM
> 
> Disadvantages: may cause weird issues / confusion with people switching 
> back to xl. The core issue is that with the current version of xen and 
> libvirt, this only works with xm (when xl is used, this can create some 
> undefined behavior). However as we have seen in some recent threads on 
> this list, people tend to mix which can cause problems.
> ...

  I've chosen the virt-install method on CentOS 5 precisely because it
is like KVM.  I was hoping it would fulfill the promise of being
hypervisor agnostic.  I'm hoping it continues to be available on future
versions of CentOS with Xen.

  Though it is a waste of resources, I make all my virtual machines,
Linux and MS Windows alike, fully virtualized.  I can then move any of
the VM's with the same virt-install --import or virsh dumpxml/edit/virsh
define process.

  When moving a VM, usually the only thing I have to do outside of
virt-install/virt-manager is add ,  or , which can
be done with virsh edit.  I don't know why some of my virtual servers
need them and other don't but I have higher priority things to think
about.

  I'm the only technical support person and I don't work 24/7.  The
graphical interface of virt-manager makes it possible for non-tech
people to see what is running and see consoles to restart any
misbehaving VM's (usually MS Windows VM's).

  I have completely eliminated my use of xm.


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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Dario Faggioli
On gio, 2014-06-12 at 22:34 +1200, Peter wrote:
> This is not a complete list of the ways you can install a VM either.  My
> personal preference is to manually create the filesystem for the VM and
> then install the OS core with yum.  Then after tweaking some config
> files you can start up the VM and finish installing whatever else you
> want with yum as well.
> 
> While I don't think that this should be the recommended install method
> it might be worth mentioning and even giving a wiki page with some
> instructions on how to do it this way.  Doing an install like this is
> actually very good for a newbie because you "get your hands dirty" and
> get a really good understanding of how yum works and the internals of
> the distro.
> 
Indeed it does!

If you're up for it, Xen wiki will be glad to host it! :-P

We've got both CentOS and Fedora categories on the Wiki, both hosting
various pages, guides, instructions, etc., but none of them (I think)
goes through the procedure you mentioned:

http://wiki.xen.org/wiki/Category:CentOS
http://wiki.xen.org/wiki/Category:Fedora

Feel free to add it! :-)

Regards,
Dario

-- 
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-
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Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)



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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Dario Faggioli
On mar, 2014-06-10 at 17:21 +0100, Lars Kurth wrote:
> Hi all,
> 
Hi!

> == #1 virt-install ==
> 
> Advantages: similar to KVM
> 
> Disadvantages: may cause weird issues / confusion with people switching 
> back to xl. The core issue is that with the current version of xen and 
> libvirt, this only works with xm (when xl is used, this can create some 
> undefined behavior). However as we have seen in some recent threads on 
> this list, people tend to mix which can cause problems.
> 
When you're saying "this only works with xm (when xl is used, this can
create some undefined behavior", that is because of the particular
version of libvirt (and Xen) is available in CentOS?

I'm asking because, with current enough versions of both, situation
should not be that bad, at least not as far as virt-install and VM
provisioning are concerned... :-O

Personally, I'm not sure whether this is the best solution, but I see it
like something that should not be left in a 'non-working' state.

Parhaps, a disadvantage I see in going for it as the default and
recommended mechanism is that you really need:
 - a recent version of libvit to start with
 - a way to update libvirt quite often, to take advantage of new 
   features being added

> == #2 xen-tools ==
> 
> Advantages: Very flexible. Many other distros use xen-tools, so we have 
> lots of beginners docs that just need to be tweaked
> 
> Disadvantages: needs porting/packaging for CentOS. Does not work for 
> kvm. Says "xen". (Maybe that's an advantage.)
> We know that xen-tools works with Fedora (see 
> http://blog.xen.org/index.php/2013/01/24/using-xen-tools-on-fedora/), so 
> the porting effort may be small
> 
Yep, and I went beyond that, and produced some spec files. This should
be the latest one, although it's for version 4.3.1 of xen-tools, so no,
not the latest possible or the tip of the repo:
http://dariof.fedorapeople.org/SPECS/xen-tools.spec

My main problem with xen-tools is that it is kind of debian (and
derivatives) biased, when it comes to building the guest file system.
I.e., last time I tried, provisioning a Fedora or CentOS guest was
possible, but not as straightforward as creating a debian one. That is
not xen-tool's fault, is the fact there were no good alternatives to
debootstrap.

However, it looks like rinse (one of said alternatives to debootstrap)
is getting some steam again:
https://gitorious.org/rinse

so that may actually be worth a try.

Also, I recently saw this in xen-tools-discuss mailing list:

"anouncement : Xen-tools update for centos 6.5"
 http://xen-tools.org/pipermail/xen-tools-discuss/2014-May/001053.html

Even if only for the title, it looks like something to investigate! :-P

> Unknowns: What would be needed to make it work for CentOS
> 
Talking a bit with Axel (xen-tools' maintainer) at the time, the main
issue in packaging subsequent versions of xen-tools for Fedora was going
to be some dependencies from a bunch of perl module he wrote, and
packaged himself for Debian, as separate packages. Nothing terrible, but
that would mean making the RPMs for those modules as well.

TBH, it is a while back, and I'm not sure what happened, whether went
that route. This link, from the xen-tools-discuss email mentioned above:
https://github.com/remsnet/xen-tools-rpmbuild

seems to have (more) updated spec files. I haven't tried them, though.

> == #3 virt-builder (http://libguestfs.org/virt-builder.1.html) ==
> 
> Advantages: supports KVM, Xen and other VM inages. Seems easy to use.
> - if so, it would avoid xm / xl confusion.
> 
> Unknowns: Not sure at which level virt-builder integrates with Xen and 
> other hypervisors. It seems to operate at disk image format (similar to 
> xen-tools) . I don't know whether virt-builder is restricted to some 
> hypervisors in RHEL7.
> 
> Disadvantages: may need porting/packaging for CentOS. It appears as if 
> it will be in RHEL7, so it may just appear with CentOS 7. If not, some 
> porting work may need to be done.
> 
Not commenting on this as I don't know it.

All that being said, and FWIW, I think I'd prefer #1, provided a recent
enough version of Xen and Libvirt could be used.

Regards,
Dario

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-
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Peter
On 06/11/2014 04:21 AM, Lars Kurth wrote:
> Hi all,
> 
> following the discussion on about documentation, I was wondering whether 
> we need to look at a standard way in which we recommend how to provision 
> images for VMs. Am starting this with a Xen hat, but the discussion 
> should not be specific to this. There are a number of options, but all 
> have some trade-offs
> 
> == #1 virt-install ==
> == #2 xen-tools ==
> == #3 virt-builder (http://libguestfs.org/virt-builder.1.html) ==
> == #4 Cloud Image from Cloud Image SIG ==

This is not a complete list of the ways you can install a VM either.  My
personal preference is to manually create the filesystem for the VM and
then install the OS core with yum.  Then after tweaking some config
files you can start up the VM and finish installing whatever else you
want with yum as well.

While I don't think that this should be the recommended install method
it might be worth mentioning and even giving a wiki page with some
instructions on how to do it this way.  Doing an install like this is
actually very good for a newbie because you "get your hands dirty" and
get a really good understanding of how yum works and the internals of
the distro.


Peter
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Peter
On 06/12/2014 05:17 PM, lee wrote:
> I knew before I started that network setup would be a PITA because years
> ago, I set up a VM for someone who didn't have a 64bit system to compile
> a 64bit version of some software.  The network setup being so
> ridiculously difficult has kept me from touching VMs ever again for
> years.  It's just too difficult and not worth the effort unless you're
> really forced to do it.

Networking can be confusing until it "clicks" then it all seems to fall
into place, there is a certain amount of understanding of the overall
picture of how bridge networking (or other types of networking) works
that once you get that understanding it becomes a lot simpler.  One
thing that probably confuses you is that there are certain parts of the
networking that are done by the dom0 distro, certain parts are done by
Xen scripts and front and backend drivers, and some parts are done by
the domu operating system.  Understanding how those parts fit together
and how different distros do the same thing but perhaps with different
configs helps a lot to getting a grasp on the whole.

Obviously better documentation would help with this, but like anything
of this nature there is a learning curve that you simply have to get
over before you can really become proficient.

> As a user, I'm used to get an ISO of an installer or of a life system,
> put that into a DVD drive or write it to an USB stick and to boot from
> that to do the installation.  Why can't I do that with xen?

You can do that with Xen, KVM, and most other types of virtualization.
The idea is that you need to block-attach the disk (or ISO file if you
prefer not to use a physical disk) to the VM and then it can be mounted
and used as install media (or any other type of media for that matter).
 This can be done from teh domain config file or from the xm (or xl)
command line.

Another quick note specifically for you.  I have noticed in past
messages that you seem to be having some confusion with xm vs xl
commands and some explanation about that is probably in order to clear
up that confusion.  xm and xl are nearly identical commands to use, but
xm is the "old" way and xl the "new" way.  Basically put, xm interfaces
with a daemon running in the dom0 (xend) which in turn interfaces with
the hypervisor, while xl uses libraries to interface directly with the
hypervisor and so eliminates the need for xend.  You will see
documentation refer to one or the other, sometimes almost
interchangeably, because the two tools have almost identical usage, but
what you should be aware of is that you really need to pick one and
stick with it, Xen does not work well if you try to use xm for some
commands and xl for others.  Since you're new I would recommend xl
because xm is deprecated in newer versions of Xen, so if you want to
future-proof your knowledge xl is the way to go.  Also if you're using
xl then you should not be running the xend daemon, this is easily
accomplished by using chkconfig and service to turn xend off.


Peter
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Dario Faggioli
On gio, 2014-06-12 at 07:17 +0200, lee wrote:
> Lars Kurth  writes:

> Let me wear the hat of the user.  The major hurdles were network setup,
> installing something in a vm, and the chaotic state the documentation is
> in.
> 
Wow... "chaotic state" :-O

Don't get me wrong. I know everything can always be improved, and
documentation is --for free software in general, which well includes
Xen-- often in a position of needing _a_lot_ of improvement.

All that being said, it would be helpful if you could be a bit more
specific and help us actually improve it. I think you've said, in
another thread, that you requested editor access to the wiki, but don't
know what status such request is in (provided I'm not mistaking you with
someone else, in which case, sorry! :-P). Can you double check, so that
we can see how to move forward and allow you to act instead of only
complaining. :-D

> As a user, I'm used to get an ISO of an installer or of a life system,
> put that into a DVD drive or write it to an USB stick and to boot from
> that to do the installation.  Why can't I do that with xen?
> 
Wait, what? Who said you can't do it? Of course you can! In fact, if you
tried and it failed, please, report the bug within the appropriate
channel, because a bug is what that is, nothing less! :-O

However, I think we're talking about something different here...

> > == #1 virt-install ==
> > == #2 xen-tools ==
> > == #3 virt-builder (http://libguestfs.org/virt-builder.1.html) ==
> > == #4 Cloud Image from Cloud Image SIG ==
> 
> I wouldn't want #4.  I want to be able to just use the installer of
> whatever distribution I'm installing in a VM and a simple way of saying
> "run this in a VM and let me install".  Or perhaps I merely want to run
> a life system in a VM to try it out, with network access.  What easy way
> is there to do that?
> 
I'm not sure I got what you mean with 'I merely want to run
 a life system in a VM to try it out'. If you mean trying out Xen in a
VM, then of course you need a nested-virt capable platform. If you have
one, here's the instructions of how to create a Xen liveCD. I'm afraid
both the instructions and the liveCD are Fedora based, but it should not
be a big deal to bias them toward CentOS:

http://lists.xen.org/archives/html/xen-users/2014-06/msg00065.html

I also don't know much of #3, but at least #1 and #2, are both meant at
doing exactly what you're saying: "install this in a VM", they only
happen not to require install DVDs. I understand that DVDs are your
preferred method, but that doesn't make it the one _everyone_ prefer!

AFAIUI, when talking about this kind of provisioning, what we're
interested is something a lot more automated and, as a consequence, a
lot less interactive than an installer.

> For example: http://wiki.xen.org/wiki/Credit_Scheduler:
> 
Ok, now we're talking! That's what I meant when asking to 'be
specific'! :-)

> "It is now the default scheduler in the xen-unstable trunk."
> 
> So is it the default in the version I'm using or what?
> 
Good point, I'll fix this.

> "The SEDF and BVT schedulers are still optionally available but the plan
> of record is for them to be phased out and eventually removed."
>
> What are those and have they been removed in the version I'm using?
>
Ditto.

> "Schedule Rate Limiting (added in Xen 4.2)"
> 
> That doesn't belong there.  It needs to go into the documentation for
> that particular version of xen.
> 
> "Timeslice (added in Xen 4.2)
> [...]
> # xl sched-credit -t [n]"
> 
> dito
> 
I don't agree. I think they do belnog. Of course, that does not mean we
can't link to them from a 'Xen 4.2' page.

> I always admire the documentation exim has ...  As to your original
> question:
> 
> > I was wondering whether we need to look at a standard way in which we
> > recommend how to provision images for VMs.
> 
> I'd suggest to start with splitting the documentation into different
> versions, one version of documentation for each version of xen.  Some
> way to get a VM running may then be discovered and improved upon.
> 
Personally, I don't think that would be the optimal split, or something
we need to do right now (which does not mean we should not improve docs
in other ways). However, I think you're way off the 'original question'
which, again, was about provisioning.

Regards,
Dario

-- 
<> (Raistlin Majere)
-
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)



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