Does anyone have any experience with mirroring a shared vg using
CSPOC? I am mirroring between two separate disk subsystems. Normally
when you disable quorum, you are required to vary off then vary on the
vg in order for it to take effect. I am being told by IBM support
that CSPOC is able to override this and make the change active without
bringing the vg offline...however, my testing shows that I still have
to vary off/on the vg in order for the vg to remain online following a
single disk subsystem failure. Is CSPOC broke, or is this normal?

CSPOC will allow you to make changes to volume group information
on all nodes when one of them may have the volume group vary'd on.

It will bypass the normal vg locking methods to accomplish that.

So....You should be able to extendvg, and perform lvm operations
through the smitty menus without needing to varyoff the volume group.

As to quorum, I think you will still need to vary off, and vary on the
volume group
to make the quorum setting active.

Hope this helps