Is it possible to boot VM guests from SAN ?

[Pulse001]

Hi All,

I have a BL870c Integrity Blade. is it possible to create VM's in this and use SAN disks to boot the guest VM's ? I have 4 HDD's and 4 cores in BL870c and i want to create 6 VM's in it. So i want to use LUN's from SAN storage box to boot the guest VM's.

is this possible to do ?

Thanks in advance.

[Torsten.]

In general yes, it is.

What is your version of HPVM?

Up to version 3.5 you need multipathing software if you want to use raw disks as backing store, otherwise IMHO the best is to use LVM lvols and present them to the guests.

[Pulse001]

Torsten i am using HPVM 4.0 . If i present logical volumes to VM guest it will be like
disk:scsi::lv:/dev/vg01/rlvol1 from VM host.

So exactly what file i will see on VM guest ? How to specify that while installing OS ?

[Torsten. · Accepted solution]

This should work without problems.

The guest see the disk as a normal scsi disk, identifier will be "virtual LV disk".

[Pulse001]

Torsten so you mean disks will show normally as /dev/dsk/c#t#d# on VM guest ?

And one more doubt that even when i am presenting SAN disks to the VM, on command line while allocating to the guest i will still have to use "scsi" ?

[Torsten.]

For the guest it is still a normal local scsi disk.

From host side you can present it either as scsi or avio (need to check if an LVOL can be avio too).

[Tim Nelson]

Concurring with Torsten.

The vGuest does not have a clue, see or care what the backingstore really is. The vHost takes care of the presentation to the vGuest.

A backingstore could be an iso file, lvol, raw disk, etc...

vGuest will always sees an atypical scsi device of some type.

example:
# ioscan -kfnC disk
Class I H/W Path Driver S/W State H/W Type Description
=======================================================================
disk 0 0/0/0/0.0.0 sdisk CLAIMED DEVICE HP Virtual FileDVD
/dev/dsk/c0t0d0 /dev/rdsk/c0t0d0
disk 1 0/0/0/0.1.0 sdisk CLAIMED DEVICE HP Virtual LvDisk
/dev/dsk/c0t1d0 /dev/dsk/c0t1d0s2 /dev/rdsk/c0t1d0 /dev/rdsk/c0t1d0s2
/dev/dsk/c0t1d0s1 /dev/dsk/c0t1d0s3 /dev/rdsk/c0t1d0s1 /dev/rdsk/c0t1d0s3
disk 2 0/0/0/0.2.0 sdisk CLAIMED DEVICE HP Virtual LvDisk
/dev/dsk/c0t2d0 /dev/rdsk/c0t2d0
disk 3 0/0/0/0.3.0 sdisk CLAIMED DEVICE HP Virtual LvDisk
/dev/dsk/c0t3d0 /dev/rdsk/c0t3d0
disk 4 0/0/0/0.4.0 sdisk CLAIMED DEVICE HP Virtual LvDisk
/dev/dsk/c0t4d0 /dev/rdsk/c0t4d0
disk 5 0/0/0/0.5.0 sdisk CLAIMED DEVICE HP Virtual LvDisk
/dev/dsk/c0t5d0 /dev/rdsk/c0t5d0

[Olivier Masse]

Yes it works, and I've been doing it a lot since HPVM 4.0 came out, using raw devices with the new storage stack (/dev/rdisk/diskXXXX). You'll get more performance than with the file backend, and it's simpler to manage than the LVM datastore. Don't forget to use AVIO if you can. Furthermore, every feature you're used to with a SAN (Busines Copy, CA, etc) can be done transparently as if it was a physical server.

Good luck

[Pulse001]

Thank you all for your knowledge sharing and guidance.