Moving mirror disks to different controller?

[Dave Chamberlin]

I currently have 3 disks (configured as 3 volume groups, each one disk) and their mirrors on the same controller and would like to be able to put the mirrors on a new (different) controller. Would I :

configure each vg to have 0 mirrors (using SAM)
install new controller
configure each vg to have 1 mirror, using new hardware addresses

Or is this more complicated?

[Carlos Fernandez Riera]

An easy way is export each vg, change hardware and import each vg again.

Using this way, you dont break your mirror, so can save many time in remirroring.

Search on this forum to get a full description of the process you must follow. There are same really good responses.

Good luck.

[Venu_2]

Hi,

>>> configure each vg to have 0 mirrors
>>> (using SAM) install new controller
>>> configure each vg to have 1 mirror,
>>> using new hardware addresses

I think this should be ok, Pl be sure of backup (DATA).

lvreduce -m 0
/dev/vgXX/lvXX /dev/dsk/disk_to_be_removed

vgreduce /dev/vgXX /dev/dsk/disk_tobe_removed

connect the disk on to the new controller

vgextend /dev/vgXX /dev/dsk/disk_to_be_added

lvextend -m 1
/dev/vg00/lvXX /dev/dsk/disk_to_be_added

goodluck

venu

[Stefan Farrelly]

You didnt say if you have 3 new disks also on the new channel, My answers below presume you do;

There are 3 ways you can do this;

1. reduce your current mirrors (lvreduce -m 0). Add the new disks on the new controller to your existing volume group, re-extend the mirror onto the new disk (lvextend -m 1). No downtime needed.

2. Add in the new disks on the new controller to your exisiting volume groups. pvmove you existing lvols to the new disks (pvmove). No downtime needed.

3. Add in the new disks on the new controller to your existing volume groups and then extend a 2nd mirror onto them (lvextend -m 2). Once this has completed remove the 1st mirror (lvreduce -m 1 /dev/dsk/c...). This is the safest way because you always have your data protected during it as well as no downtime needed. With method 1. or 2. above you are at risk of a disk/controller failure during the procedure which could cause data loss.

[Evan Day]

If one of these mirrored pairs you're moving is your root disk, be sure to make the new mirror bootable, with the proper autoboot string, (pvcreate -b, mkboot -a "..." - the HP-UX 10.* System Administrations Tasks manual has a chapter on this, applies to 11.0 as well, http://www.docs.hp.com)

I did this myself a while back and ended up doing something similar to what everyone else suggested, I vgexported everything except vg00, moved one side of the mirror, then used vgimport to bring everything back. For vg00, it's probably easiest to just break mirrors with lvreduce, move the disks, then remirror everything. I won't detail what I went through - it was a learning experience that I wouldn't subject anyone else to :) Suffice to say I was lucky I had a big maintenance window.