Comments on: In theory – migrating from Xen to KVM under CentOS 5.3 http://www.thatchrisbrown.com/2009/in-theory-migrating-from-xen-to-kvm-under-centos-5-3/ Another Chris Brown & another blog Sat, 17 Oct 2009 11:36:58 +0000 http://wordpress.org/?v=abc hourly 1 By: Chris http://www.thatchrisbrown.com/2009/in-theory-migrating-from-xen-to-kvm-under-centos-5-3/comment-page-1/#comment-62 Chris Sat, 17 Oct 2009 11:36:58 +0000 http://www.thatchrisbrown.com/?p=107#comment-62 Hi Jeff! I'm casting no doubts on the Gitco repos at all - they've served me well and tge box is still unmigrated and running Xen! I had a bit of a nasty experience when I did my first yum update with Gitco repo enabled - no VM guests could start after reboot! At the time I just hacked grub back to an earlier kernel and put it down to inexperience. Fairly recently I discovered that I'd got repo priorities a bit wrong, fixed that and did a manual rpm cleanup of the mess I'd made for myself. Currently, after a paranoid triple-check of repo priorities, installed kernels and Xen versions, I felt confident enough to let yum do it's trick, and I have an updated and running dom0! I noticed an oddity with grub not always being updated correctly, so I always scan it now before rebooting after an update - I'll post on that when I understand it better... When I get my other host up, I'll hope to do some Xen/KVM comparisons & see what comes out. Either way, Red Hat are likely to push KVM harder in future. Could be an interesting competition! Cheers, Chris Hi Jeff!

I’m casting no doubts on the Gitco repos at all – they’ve served me well and tge box is still unmigrated and running Xen!

I had a bit of a nasty experience when I did my first yum update with Gitco repo enabled – no VM guests could start after reboot! At the time I just hacked grub back to an earlier kernel and put it down to inexperience.

Fairly recently I discovered that I’d got repo priorities a bit wrong, fixed that and did a manual rpm cleanup of the mess I’d made for myself.

Currently, after a paranoid triple-check of repo priorities, installed kernels and Xen versions, I felt confident enough to let yum do it’s trick, and I have an updated and running dom0!

I noticed an oddity with grub not always being updated correctly, so I always scan it now before rebooting after an update – I’ll post on that when I understand it better…

When I get my other host up, I’ll hope to do some Xen/KVM comparisons & see what comes out.

Either way, Red Hat are likely to push KVM harder in future. Could be an interesting competition!

Cheers,

Chris

]]> By: Jeff http://www.thatchrisbrown.com/2009/in-theory-migrating-from-xen-to-kvm-under-centos-5-3/comment-page-1/#comment-61 Jeff Sat, 17 Oct 2009 09:39:44 +0000 http://www.thatchrisbrown.com/?p=107#comment-61 Hi Chris, why did you say "5.2/5.3/Gitco hybrid horror treatment"? Since month I work with the GITCO repo and had never problems with it. Dom0 is CentOS5.3 (x86_64) and the DomUs are Windows2003-2008 (GPLPV), Debian Lenny, CentOS5, Opensolaris. I work with HVM and PVM machines without an errror. The performance is very good. I had never such a performance with KVM! Thanks Jeff Hi Chris, why did you say “5.2/5.3/Gitco hybrid horror treatment”? Since month I work with the GITCO repo and had never problems with it. Dom0 is CentOS5.3 (x86_64) and the DomUs are Windows2003-2008 (GPLPV), Debian Lenny, CentOS5, Opensolaris. I work with HVM and PVM machines without an errror. The performance is very good. I had never such a performance with KVM! Thanks Jeff

]]> By: Chris http://www.thatchrisbrown.com/2009/in-theory-migrating-from-xen-to-kvm-under-centos-5-3/comment-page-1/#comment-19 Chris Tue, 28 Jul 2009 17:10:08 +0000 http://www.thatchrisbrown.com/?p=107#comment-19 Since writing this, I've realised that because I installed my Xen guests with virtual disks in LVM logical volumes, they've been installed the same way as they would if they were physical drives instead of an image file - they have a /boot partition, a swap partition and a / partition, and dd says the first block looks the same to the dom0 as it does to the domU. Perhaps I'll be able to just stick a plain kernel on, make that default before shutdown and then fire them up under KVM straight from the logical volume with no messing about. Fingers crossed! Since writing this, I’ve realised that because I installed my Xen guests with virtual disks in LVM logical volumes, they’ve been installed the same way as they would if they were physical drives instead of an image file – they have a /boot partition, a swap partition and a / partition, and dd says the first block looks the same to the dom0 as it does to the domU.

Perhaps I’ll be able to just stick a plain kernel on, make that default before shutdown and then fire them up under KVM straight from the logical volume with no messing about.

Fingers crossed!

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