AIX

I seem to recall there might be a way...but I am thinking old hacmp where there might have been a way to take the odm entries from the live system and update the odm on the old system. Not sure.

Ok. I had a thought - would this work?

Can I add new disks to the primary, create a new shared VG using the new disks, and then somehow migrate the VG contents to the new VG and get rid of the old VG (while the VG is active)?

Thanks.

Hello there,
After reading your post I assume that you wanted the newly created VG to be shared,
For that you need couple of things,
The reserve policy of each disk under that VG should be 'NO' and the VG must be concurrent capable.

Now, you can add a new VG, LV and File system to a cluster without bringing it down or causing a failover. use CSPOC to add a VG to your cluster.

So, before creating vg, on each disk run chdev -l hdisk -a RSV=no (where RSV=reserve_lock or policy depending upon your storage).

Now, you CSPOC to create a new VG, it will create a vg and what even you want (like LV and FS) and also sync the cluster, meaning updating the same info at the passive node.

I do not have an "HACMP" (v1-v5) (aka PowerHA (v6) aka System Mirror (v7)) handy, but since HACMP v5 volume groups are meant to be "enhanced concurrent".

What this means in "AIX speak" is that the VGDA is open on both sides so that when the active side makes a change to the volume group that inactive (passive) side can update the ODM with the data - which speeds up the takeover time when either moving a resource group manually of during a failover. The reason being - getting the VGDA (read ODM) data current during a move was often 30-50% of the time needed for a move. "Enhanced" concurrent speeds this up.

You should be able to synchronize the resource groups. You may get an warning about not being "enhanced concurrent" - but this means your move/failover will take longer.

To make it enhanced concurrent you will need to stop the application so the volume group can be varied off and then on again.

p.s. when a disk is part of an enhanced concurrent vg it can be used for a non-IP network for passing a heartbeat. This is changed, I do not know the details, in SystemMirror (v7) as it uses CAA (Cluster Aware AIX) rather than RSCT for topology monitoring.

Hope this clarifies it enough for you, and the AIX speak was not too difficult :wink: