Originally posted by: Chris_Scoffield

We have a requirement to make a expand a LUN (DS4800) however this LUN is is allocated to a volume group as part of a HACMP cluster.
Does anyone have any ideas how to go about doing this other than taking the cluster offline and running a chvg -g on all cluster nodes

Originally posted by: j.gann

as of today, if the VG is varied on in EC mode "chvg -g" does not work (see man chvg). To my knowledge some IBM customers already have requested a design change to make this possible.

If you can't afford a downtime, you have some options though:

• extend your vg with additional pvs
• add new (larger) pvs, mirror and drop the original (smaller) pvs
• kinky and unsafe unless you have 3 mirror copies, I have not tested this personally: if the vg is a RAID 1 mirror, you might even remove individual (mirror copy) pvs from the vg, remove the pv and let cfgmgr reconfigure it to the new size, add it to the vg again, mirror and do the same for the rest of the mirror copies.

Regards
Joachim Gann

Originally posted by: SystemAdmin

I did use a third copie (you need disk space) to remove a copie, remove the disque from the VG.
The disque can be simply removed and re-created by a
rmdev -l hdiskXYZ && mkdev -l hdiskXYZ
The disk name doesn't change
Putting the disk back in the VG and created a third copy (became second copie when the copy on the temp disk is removed).
it's long, but safe.