temporarily break mirrors on MCSG cluster

[TMcB]

hello everyone.

Our volumes are mirrored using MirrorDisk.
Our SAN team have told us they need to perform maintenance on one of the disk arrays, and that we will need to stop I/O while they do this.

Just want to confirm I will need to do the following :

for each LV :
lvreduce -m 0 /dev/vgXX/lvXX /dev/dsk/cXXXXX

The MCSG cluster will stay up.
Then when the SAN guys have finished their maintenance, run :

lvextend -m 1 /dev/vgXX/lvXX /dev/dsk/cXXXXX

Is this all I need to do?
Thanks for your help.

[Stephen Doud · Accepted solution]

Depending on the maintenance that will be performed, you should not have to reduce the mirrors off of the disks in the array that will be experiencing maintenance. LVM Mirror/UX should be able to resync mirrors that go stale as a result of being offline.
Since you choose to disassociate them from data volumes, that should be sufficient. Once the maintenance is complete, you can re-mirror the volumes to the array. No LVM-related files on either system are changed as a result of demirroring or re-mirroring.

[TMcB]

Hi

The firmware is being updated on the SAN disks - and they have asked us to ensure no I/O while this is going on.

thanks for your reply

[Siju Vadakkan]

You don't need to remove the mirror.

Here are the steps

1. Identify the disks that are used as mirror disks

and then deacivate those disks using pvchange command, this will make the PE's belonging to those disks stale.

#pvchange -a n

2. Once ur storage team completes there task, the only thing what u need to do is, just activate the PV again. It will sysn automatically.Incase if it didn't sysc , sync it using "vgsync vgname" or logival volume wise by "lvsync lvname"

#pvchange -a y
#vgchange -a e

"-a e " becz u said it is activated by SG.

[TMcB]

thanks for letting me know

[Siju Vadakkan]

points please