On Wed, Mar 31, 2010 at 03:43:38PM -0400, Grant McWilliams wrote:

On Wed, Mar 31, 2010 at 11:38 AM, Pasi KÀrkkÀinen <[1]pasik@iki.fi> wrote:

 Hello,

 RHEL 5.5 has been released, and it contains many Xen related fixes.

 Here's the most important of the them.. fixing a dom0 caching bug which
 could cause domU disk corruption when the domU disk was accessed from
 dom0
 after the domU was shutdown. Most people noticed this bug when pygrub
 used wrong (cached) information.

 "pygrub uses cached and eventually outdated grub.conf, kernel and
 initrd":
 [2]https://bugzilla.redhat.com/show_bug.cgi?id=466681

 And some more:

 "Xen hypervisor doesn't mask xsave feature from the guest; Fedora 11 PV
 domU kernel crashes":
 [3]https://bugzilla.redhat.com/show_bug.cgi?id=524719

 "[RHEL-5 Xen]: F-11 Xen 64-bit domU cannot be started with > 2047MB of
 memory":
 [4]https://bugzilla.redhat.com/show_bug.cgi?id=502826

 " Boot hang when installing HVM DomU":
 [5]https://bugzilla.redhat.com/show_bug.cgi?id=524052

 "[RHEL5 Xen]: PV guest crash on poweroff":
 [6]https://bugzilla.redhat.com/show_bug.cgi?id=540811

 "[RHEL5 Xen]: Cpu frequency scaling is broken on Intel":
 [7]https://bugzilla.redhat.com/show_bug.cgi?id=553324

 RHEL 5.5 kernel changelog:
 [8]http://rhn.redhat.com/errata/RHSA-2010-0178.html

 Work-in-progress (Not yet in 5.5):

 "Grub2 guest support for RHEL5 Xen pygrub":
 [9]https://bugzilla.redhat.com/show_bug.cgi?id=577511

 -- Pasi

Are these changes in the kernel or changes to the installed Xen? I'm wondering if this effects anyone using Xen 3.4 or newer.

I think they're mixed.. you need to go through the bugzillas to figure out. (and possibly compare to the kernel changelog above).

-- Pasi

On Thu, Apr 01, 2010 at 09:19:34AM +1100, Norman Gaywood wrote:

This may be a dumb/FA question but how do you run Xen 3.4+ with the latest Centos kernel?

And maybe another dumb question...

What's the difference between xen.org's 3.4.x series and Citrix Xenserver 5.5?

On Thu, Apr 01, 2010 at 09:08:42AM +0300, Pasi Kärkkäinen wrote:

On Wed, Mar 31, 2010 at 06:29:51PM -0400, Stephen Harris wrote:

...

On Thu, Apr 01, 2010 at 09:19:34AM +1100, Norman Gaywood wrote:

...

This may be a dumb/FA question but how do you run Xen 3.4+ with the latest Centos kernel?

And maybe another dumb question...

What's the difference between xen.org's 3.4.x series and Citrix Xenserver 5.5?

xen.org 3.4.x is just/only the core hypervisor, while Citrix XenServer 5.5 is a full 'vmware esx-like' product.. aka full distro including multi-host pool gui management tools.

And to add.. RHEL5/CentOS5 is a general purpose OS, which also includes virtualization (Xen).

Citrix XenServer is a *dedicated* virtualization platform, only built and tested for that purpose.

-- Pasi

"compdoc" compdoc@hotrodpc.com writes:

When Red Hat picks a release of kernel, xen, kvm, etc., they tweak, change, and test it until its 'enterprise' ready. If they say you can run a business class server with it, I believe them. Based solely on how well centos works.

Even though RHEL 5.4 doesn't have the newest of anything, it does what it does well. Even if I have to put up with fewer features or fixes than the current version, I'm leaving it alone.

I'm sure there are guys that can install newer releases of everything needed to run the latest xen, and it might be stable, it might not.

In my experience (several hundred RHEL xen boxes, and maybe 40 xen.org xen boxes over five years.) until recently, the xen.org xen kernel was quite a bit more stable than the RHEL xen kernel. (I mean, it didn't crash, but you'd have weird hangups with things like xenconsoled dying, or a guest's network suddenly no longer passing packets.)

The RHEL xen kernel has been getting markedly better over time, though, and the RHEL xen kernel has /much/ better driver support than the xen.org 2.6.18 kernel. My next server at prgmr.com will likely have either the the CentOS xen kernel or the opensolaris xvm xen kernel rather than the xen.org xen kernel for that reason (assuming I can get PVGRUB working and that paravirt ops linux guests work, which I believe they do.)