Mistake on vgcreate

[Tim Medford]

Last weekend I created a number of new volume groups on a Nike disk array. On one of the vgcreates, I accidentally reversed the order of the primary/alternate device files.

mkdir /dev/vg04
mknod /dev/vg04/group c 64 0x040000
vgcreate /dev/vg04 /dev/dsk/c5t6d4 /dev/dsk/c2t6d4

I should have put the c2t6d4 device file first, and then had c5t6d4 as an alternate link. As a consequence of all this, I have one controller carrying a lot more traffic than another.

Question: Is there any way I can reverse the primary/alternate device paths without completely dropping all the LVM structures and rebuilding it from scratch?

Thanks in advance!
Tim

[Iain F. Brown]

It is easy to change primary and secondary links just vgreduce primary link, secondary link becomes primary link then vgextend the vgreduced link and it becomes secondary link.

[Eileen Millen]

I haven't tried this yet.

pvcreate -s /dev/dsk/cXtXdX
to make it become the primary

I added some EMC disks with SAM and couldn't see a way to pick the primary and alternate path.
Eileen

[James R. Ferguson · Accepted solution]

Tim:

If all you want to do is swap the alternate links, simply do a 'vgreduce', as for example:

# vgreduce /dev/vg?? /dev/dsk/c?t?d? # current primary link

# vgextend /dev/vg?? /dev/dsk/c?t?d? # add back old link now as the alternate

Regards!

...JRF...

[Eileen Millen]

Sorry, that should be pvchange, you can check the man page on it.

You have to umount the disks to do it.