[rhelv6-list] How can I uniquely identify my disk in RHEL6 installed on Citrix Xenserver?

[Herbert van den Bergh]

On 11/1/12 6:55 AM, Lamar Owen wrote:
> On Thursday, November 01, 2012 05:07:17 AM John Haxby wrote:
>> On 1 November 2012 06:30, neo3 matrix <neo3matrix at gmail.com> wrote:
>>> So, Can you tell me a way out to map disks on different systems?
>> Basically, you can't.   Hardware discovery is not deterministic.   There's
>> no reason why sda and sdb (say) should be assigned to the same physical
>> disk on successive reboots of a single machine.   If you're moving disks to
>> a different machine, even if it's an identical machine with the controllers
>> in the same slots there's even less chance.  You cannot ever rely on
>> /dev/sda being a particular disk.  Period.
> Let me echo this.
[snip]
> If you rely on /dev/sdX being constant or even predictable on EL6 you're in
> for a rude awakening.
>
This is all very true for bare metal machines.  But Neo was talking 
about XenServer guests.  Those do have deterministic device names. The 
host may not, but that's a different issue.  I'm assuming he's talking 
about the scsi address that the guest OS reports, not the host.  Which 
is weird, because why would you bother with a scsi address if you know 
that the device name is deterministic.

If the user can map the virtual disks on server A to server B, why not 
do the restore on the server instead of in the guest?  If the disks that 
are being restored are OS disks, the guest can't boot from them.  So how 
does the restore get started in the guest?  Via pxeboot or something?  
Why bother with this, when you can just do this in dom0 with a simple cp 
or dd command.

Thanks,
Herbert.