topic Question regarding LVM in Operating System - HP-UX

Question regarding LVM

Bala C — Tue, 12 Oct 2010 16:36:10 GMT

We have 3 hp-ux IVM's rx6600 seeing the same Luns(Disks)

There is no service guard .

Disks ( majority ) are 80GB size … it is used for VM…. VM=disk

If a disk is being used on any VM, I am able to use the same disk to boot up on another host of the same VM ( have to go into single mode and do steps before it boots) .

However, I know there is a solution with Service Guard….

How can I prevent another host from grabbing the disk while the disk is being used by one VM?

SAN team has said that if they had made the luns marked as bootable luns, than no one can grab it (???)

If there was service guard, it would manage the rights to the disk….. since there isn’t service guard,,,, what option do I have ??

Re: Question regarding LVM

Emil Velez — Tue, 12 Oct 2010 22:58:36 GMT

to do HPVM online or offline migration to another VM host you have to have the VM boot disks whether they are Logical volumes, luns available on both systems.

Usually when you are using migration you would not use LV or files for a VM disk you would just make a lun seen by both systems.

You are right no locking of disks not even with serviceguard.

ServiceGuard only locks volume groups and disk groups that packages use. But to do online migration you probably would not use a volume manager with the disks that VMs use.

Re: Question regarding LVM

Viktor Balogh — Wed, 13 Oct 2010 13:24:33 GMT

Hi,

Try to do it the way ServiceGuard would do:

set the cluster-aware flag on the volumegroup:

# vgchange -c y vgname

for the above to work you need to deactivate the vg.

after that, a specific node can activate the volumegroup in exclusive mode, that means that the other machines can activate it only in read-only mode.

Tell me if it works.

Re: Question regarding LVM

Bala C — Wed, 13 Oct 2010 15:10:41 GMT

Thanks, Emil. I will come back to you on this.

Re: Question regarding LVM

Bala C — Mon, 18 Oct 2010 00:46:40 GMT

Folks,

But In order for making the VG cluster aware and activate in exclusive mode, the SG software needs to be installed, right?

Also, Even if the VG is activated in exclusive mode, The other Vm can still boot with the lun/disk used by this vg. As it is not going to write to the boot disk, Correct? Because still the disk under this vg are readable.

Please clarify.

Re: Question regarding LVM

Torsten. — Mon, 18 Oct 2010 08:01:07 GMT

The basic idea of a cluster aware VG is to share the data between several hosts, but not the boot VG.

So please clarify if the VM should be a SG node or should the VM itself be the package.

Re: Question regarding LVM

Bala C — Mon, 18 Oct 2010 09:49:02 GMT

The problem here is when the VG is activate in vm1, the vm2 uses the same lun/disk in vg1 to boot.

I.e. If a disk is being used on any VM, I am able to use the same disk to boot up on another host of the same VM ( have to go into single mode and do steps before it boots) .

How can I prevent another host from grabbing the disk while the disk is being used by one VM?

SAN team has said that if they had made the luns marked as bootable luns, than no one can grab it (???)