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Re: [Xen-users] Migrating XEN VMs on CentOS 4.4 to CentOS 5

G'day All,

I read/heard(?) somewhere that xvda was the future and use of hda, sda, etc. was going to be phased out. My main aim was to move xensource 3.0.3 VMs onto CentOS-5 (2.6.18-el5xen or subsequent kernel). At present I have given up on the XEN distributed in CentOS 5 and started working with XEN 3.1.0. However, I would still be interested in knowing how to migrate VMs to the distribution installed XEN. I tried an "xm migrate ..." but it didn't work (my XEN is setup for host-to-host migrations and they have worked in the past). I have also tried using the same xen configuration file and moving contents of the logical volumes around but the VM won't boot on the new system.


Wayne Mallett

On 10/05/2007, at 6:22 PM, Geert Janssens wrote:

On Wednesday 9 May 2007 19:52, Nico Kadel-Garcia wrote:
Wayne Mallett wrote:
G'day All,

I have a number of VMs that I installed on CentOS 4.4 with custom dom0
and domU kernels.  All VMs reside on logical volumes and a
disk = [ 'phy:/dev/vg0/name,sda1,w', ...]
type entry can be found in the XEN configuration file.  I have been
searching on and off for a week (no success)  trying to find out how
to move these VMs onto a CentOS-5 system - using the XEN
implementation that comes with this O/S.

I suppose what I'm asking is how do I move existing VMs from sda to
xvda disks within XEN.

Don't bother. Simply continue to use them as "sda" devices, which is
what I do. Also, getting a non-standard kernel to operate correctly in
paravirtualizd mode is going to be fun for you! I wound up using the
xensource published kernel-xen-2.6.16 kernel for this.

If you really need to migrate to /dev/xdva names, you'll need to edit
/etc/fstab on the / partition to match the new layout, and edit your Xen
configuration file appropriately.

... And on top of that, the grub menu in the domU /boot/grub directory should be updated to use /dev/xdva names. If not, pygrub will not work correctly
(presuming you are using pygrub, at least).

That was a problem I ran into.


Dr. Wayne Mallett
High Perf. & Research Computing Support
Information Technology & Resources
James Cook University
Townsville  Qld  4811

Ph (int):  5084
Ph (ext) :  07 4781 5084
Email:  Wayne.Mallett@xxxxxxxxxx

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