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

[Grzegorz Witkowski]

Use UUID and/or WWN when refering to block devices. They are consistent.

Regards,
Grzegorz
On Oct 19, 2012 7:35 a.m., "neo3 matrix" <neo3matrix at gmail.com> wrote:

> Hi all,
>
> I have installed RHEL6 as guest OS on Citrix Xen Server. After
> installation of OS, I can see disk names as /dev/xvda, /dev/xvdb instead of
> traditional convention like /dev/sda, /dev/sdb on guest OS.
>
> Generally, on physical machines, in /proc/scsi/scsi file, we get a unique
> entry for every disk connected to the system. For e.g. string
> "scsi02:00:00:01" indicates that this disk is connected to the machine via
> Host=2, Channel=00, Id=00 Lun=01. This helps me in my project to uniquely
> identify each and every disk in scenarios where many times after reboot OR
> in SAN boot cases OR in some Disaster Recovery procedures, disk names might
> change from say /dev/sda to /dev/sdb after reboot. But, this
> Host:Channel:ID:Lun combination remains same for every disk and I can
> uniquely identify the disks though their /dev/sd* names have changed.
>
> For my project, on Citrix Xenserver, I need to know the unique disk
> location for such Xen guest OS devices by which I can easily identify disks
> across the reboots for the above mentioned cases.
>
> So, I have couple of questions on this front. Please help me out or guide
> me for the same.
>
> 1. As /proc/scsi/scsi don't have such entry for /dev/xvdX type disks, do
> we have similar mechanism in Citrix XenServer to identify our guest OS
> disks uniquely?
>
> 2. This question is rather a continuation of previous one. While searching
> answer for above question, I found that for every /dev/xvdX disk, a unique
> device entry is present in /sys/block/xvdX/ directory in the format
> "vbd-XXX", for example, vbd-768, vbd-832, etc. Here, vbd stands for Virtual
> Block Device.
>
> But what is the significant of the numbers 768, 832 ,etc.? How these are
> generated? Are they indicating something like Host:Channel:Id:Lun? Can I
> trust these numbers to distinctly identify my disks? Are these numbers
> differ from one guest OS to other OR depend on Xenserver configuration?
>
> Please suggest me some answer/guideline on this front.
>
>
> Regards,
> Neo
>
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