Upgrade-downgrade howto with mirrored disk system

[Balint Tar]

Hi,

We have HP-UX 11.11 system with two internal disks, which are mirrored with LVM.
what I would like to do is the following:
- break mirroring (diskA - diskB),
- boot from diskB
- upgrade the OS (with a complex HP bundle patch set) of diskB
- test the newly upgraded system on diskB
-->if it is OK, then mirror the content of diskB to the previous root disk (diskA)
-->if not OK, than boot again from diskA, and mirror back its content to diskB (original situation)

I tried out a lot of commands, scenarios, but unfortunately none of those were successful.
What I did:
1. - break mirroring (lvreduce) --> remove diskB from vg00 (vgreduce) --> create new vg (vg0x) --> vgextend with diskB (without running the pvcreate on diskB) --> trying to mount the root system lvolx from vg0x and modify the fstab to change the vg00 lines to vg0x (prepare to boot from diskB) ===> did not work
2. - boot from diskB --> put diskA offline (pvchange -a N diskA) --> upgrade diskB ===> somehow did not work
3. - boot from diskB --> break mirroring ---> put diskA offline (pvchange -a N diskA) --> upgrade diskB ===> somehow did not work also

Please advice or comment.
Thanks in advance.

BR,
Balint

[A. Clay Stephenson]

lvreduce/vgreduce simply removes your mirrors and renders them useless. You do not want to do this.

The safest method is to shutdown and remove your alternate boot disk and then do a boot. If you have already altered your primary boot string to allow quorum override (-l q) then you can allow the machine to boot normally. If not, you will have to interrupt the boot process, boot primary, Interact with ISL> Y
then
hpux -lq /stand/vmunix

You can then do your upgrade and resync the VG when finished.

My method is to actually create a lifeboat disk and then go ahead and do your patching with the mirrors intact. If anything goes wrong, you move your lifeboat to the boot slot and you boot normally and are back where you were before the patches.

[Bill Hassell]

Have you previously tested that your boot disk was properly setup to boot from the mirror? The second disk will not boot if you did not create the mirror without running the mkboot command, it will never boot. Once both disks boot by themselves you can then remove one and boot up to make your changes.

[Balint Tar]

Thanks for the quick answers.
A. Clay Stephenson:
Yes, you are right, that is the safest way, but we are restricted not to remove any disk from the box. Unfortunately it seems to me it is not possible to put a disk permanently offline by any commands through reboots.
I really do not know why my '1.' procedure fails, I think it should work. After extending the new vg with the previous mirror disk (diskB), the LVs should pop up. In that case finally I would have two VGs (the original one, vg00 and the newly created, vg0x) with the same content, but not mirrored, and the upgrade could be done in a safe way.
Bill Hassell:
Yes, of course. The mirror disk (diskB) was prepared properly with mkboot commands and the system can be booted from both disks smoothly.

Balint