LVextend problem

So, we are facing problem with extending LV...
We had 2x300GB in mirror on IBM Xserver for rootvg.
We failed one of the disks and replaced it with 600GB, rebuild it and did it with the other disk the same...
Extended Virtual drive on RAID to 600GB. After that we have shut down the server and removed one of the disks. The Array was marked as degraded, but never the less, we could boot to OS. PVresize worked like a charm, but after lvextend server started to act strangely...after reboot it did't make it to OS anymore... Any ideas why this could be a problem? And how to extend it successfully?
We made a "recovery" plan, inserted other (good) disk in the server, imported foreign config, started the OS, inserted "non working OS" disk and did a rebuild. So we have some kind of reversible plan, but would like to increase the size of rootvg. We are running TSM on this server and all other disk slots are occupied (otherwise we would make desired sized rootvg on other disks).
Anyone faced the same problem?

I always try to keep the rootvg to a minimum, after all, how do you plan to use mksysb to save a bootable OS media for an emergency recovery?

Just 8Gb should be plenty for AIX operating system with space to spare. Make the OS disk simple.

Keep all your user personal space, and application space in a separate volume group.

I know that there are costs with having more media, but it's well worth it. You need to ask yourself 'Is �1,000 GBP / $2,000 USD etc. worth losing my server for?' and do the job well. Of course, it will then be tempting to fill the rootvg with other stuff, just because there is space there, but you are immediately compromising yourself.

The other way to do this would be to have the disks mirrored by the hardware and provide logical disks to the operating system. That way, you get the best of both worlds, but you need to know you can tell when a disk has failed and has left you exposed.

Can you confirm:-

  • how your resized?
  • if the logical volume copies were synchronised or were any stale?
  • if you re-created the boot loader for the OS on the new disk(s)?
  • if you put the disk into the boot list?
  • what you can see from SMS / firmware prompt?

Hopefully we can help you here.

Kind regards,
Robin