Where to put the VM guest O.S's root vg , local disk / san

[Amit Jindal_1]

Hi,
I am planning to use BL870C with IVM, the server has 4 local SAS disks, I have gone through some documentations and found that the VMHOST will require a RAW device ( boot device ) which can't be presented to guest os's. Then I assume the the disk ( lv's) has to be mirrored so 2 of my local disks are gone for VMHOST.

1)Can i use a SAN LUN as a physical backing store on guest OS on which OS ( root vg) will be installed ?
2)What is advised ? to put the guest O.S root vg on local disk or SAN LUN ?
3) If I can't use SAN LUNs for guest O.S root vg then within the two leftover disks how many O.S's i can carve out without feeling the I/O slowdown. Again the guest O.S'es root vg will require mirroring.

[melvyn burnard · Accepted solution]

>1)Can i use a SAN LUN as a physical backing store on guest OS on which OS ( root vg) will be installed ?

Yes you can, the backing store for a VM can be (as seen by the VM Host) a physical disk, a LUN on the SAN, a Logocal Volume, or a file on a file system.


>2)What is advised ? to put the guest O.S root vg on local disk or SAN LUN ?
It depends on what you have, and what you want to do. I recommend you read through the documents available at:
http://docs.hp.com/en/vse#HP%20Integrity%20Virtual%20Machines

[Tim Nelson]

1) you can use any disk based backing device that you wish. Your choice. If you use protected array luns then you do not need to worry about mirroring or anything.

2) Then configure your sas disk with mirroring and present either whole device or lvs carved out for each guest.

Performance of your OS disk is not typically a huge consideration. Other than log files, what are you writing to the OS ? not much. Maybe if you poorly configure your guests and they swap, but that is a different issue.

A happy mix of the resources you have available to you is typically the answer.

[Amit Jindal_1]

Thanks for the quick answers again.