Just a thought (and trying to avoid downtime) can you not add the new LUNs into the VG and then migrate them with the server still live? I've done this very successfully and prevented needless hours of downtime (three weekends-worth)
The team I was helping to do this were very nervous and wanted the belt & braces approach so we:-
- Added the new LUNs to the VG
- Mirrored the LVs (no sync) and confirmed the layout was correct (not spread to old disks etc.)
- Ran a syncvg and left if. Any problems, we would drop the new leaving the old intact.
When it had completed, we:-
- Removed the mirror from the old/original disk
- Removed the original disks from the volume group
Like I say, this was done with the server online and processing. The volume manager deals with this very well, and whilst it takes a long time to synchronise, it's probably no worse than waiting for something else to migrate the data. It is also reversible up to the point you commit by removing the mirror copies on the old disks.
Why do you not want to have both SANs connected at the same time? The usual arrangement is to have the SAN connections passed through a switch rather than direct to the AIX host. Is there a reason that you could not just add the new SAN connections to these switches?
I hope this gives you an alternative,
Robin