topic Re: Spliting mirrored root disk in Operating System - HP-UX

Spliting mirrored root disk

Jay_122 — Fri, 14 Jan 2005 16:11:42 GMT

I am going to be applying patches and would like to split the mirrors on my root disk to save a copy as a backup. What is the best way to do this? I have already created an ignite tape. Any help would be appreciated.

Re: Spliting mirrored root disk

Mic V. — Fri, 14 Jan 2005 17:11:43 GMT

Assuming you're using MirrorDisk, check out lvreduce (lvreduce -m 0):

man lvreduce
http://docs.hp.com/en/B2355-60103/lvreduce.1M.html

This might make interesting reading:

http://docs.hp.com/en/5990-8172/ch06s02.html#cdebgaei

Regards,
Mic

Re: Spliting mirrored root disk

A. Clay Stephenson — Fri, 14 Jan 2005 17:44:11 GMT

lvreduce -m 0 will remove the mirroring -- not exactly what you want to do should you need to replace the original data.

First, I'll assume that you have done a
mkboot -a "hpux -lq (;0)/stand/vmunix" /dev/rdsk/cXtYd0 on both your primary and alternate boot disks so that you can boot from either one without quorum. Next, shutdown and remove/disconnect the alternate drive. You can now reboot and install your patches. When you are finished, shutdown and reinstall the removed disk and boot. Issue a vgsync /dev/vg00 and you are done.

However, this is NOT the way I do it because I never want to leave any drive unmirrored so my method is to do a raw disk copy of the primary drive to an identical disk to create a lifeboat.

Re: Spliting mirrored root disk

Camel_1 — Sun, 16 Jan 2005 04:33:27 GMT

consider to run ignite backup before making any OS change.

Simon

Re: Spliting mirrored root disk

Trond Haugen — Mon, 17 Jan 2005 05:27:54 GMT

I would recomend BOTH splitting the mirror AND Ignite backup.
After all two different backup/fallback methodes are better than one.

Regards,
Trond

Re: Spliting mirrored root disk

Florian Heigl (new acc) — Mon, 17 Jan 2005 06:56:31 GMT

Shutdown
Remove the mirror disk
boot with hpux -lq
Patch
reboot
test

Reinsert the mirror disk,
ioscan -fnCdisk # disk found?
for lv in `vgdisplay -v /dev/vg00 | grep "LV Name" | awk '{print $3}'`
do
lvsync $lv
done
lvdisplay /dev/vg00/lvol* | grep -c stale
# must return 0

Re: Spliting mirrored root disk

Florian Heigl (new acc) — Mon, 17 Jan 2005 06:59:15 GMT

Uh, maybe I should better add this for clarity :)
if 'test' fails, shutdown and boot with -lq from the mirror disk only, then sync to the old 'original'

Re: Spliting mirrored root disk

Geoff Wild — Mon, 17 Jan 2005 08:54:24 GMT

You can use lvsplit, apply patches, reboot (more then likely) and if happy - lvmerge.

lvsplit - split mirrored LVM logical volume into two logical volumes

lvmerge - merge two LVM logical volumes into one logical volume

man them for more info

Rgds...Geoff

Re: Spliting mirrored root disk

Jannik — Mon, 17 Jan 2005 10:20:00 GMT

have a look at this:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=717548

Re: Spliting mirrored root disk

Jay_122 — Wed, 18 Apr 2007 09:47:38 GMT

Thanks to all!!