If you are jumping from AIX5.3 to AIX6.1, then it is called migration.
Since you are saying the rootvg is mirrored, you can use one disk for migration keeping the other on current OS version.
I recommend using NIMADM (only reboot require downtime, rest can be done when the system is up).
Steps:
Break the rootvg's mirror
unmirrorvg rootvg <hdiskname>
If you still see some LV mirrored you can run
rmlvcopy <lvname> <no of copies (1)> <pvname>
Now that the rootvg is unmirrored, run
reducevg rootvg <hdiskname>
recreate the boot image (safe side)
bosboot -a -d /dev/<hdiskname>, here hdisk is the disk on which you have your rootvg
then
bootlist -m normal -o <hdiskname>
Coming to actual migration, you need
- NIM Server (alteast at AIX6.1 TLXSPX (the OS, TL & SP Version of NIM should be higher than its client or same level post migration)
- Make sure it can talk to client (check the nimsh service etc..,)
- Make sure you have an empty disk (this is the one you just freed)
- Make sure on NIM you have AIX6.1 as LPP Source and SPOT
After confirming all the above and their dependencies, proceed with the below. From NIM Server run
smitty nimadm --> Perform NIM Alternate Disk Migration
* Target NIM Client [Client name] +
* NIM LPP_SOURCE resource [61_lppsource] +
* NIM SPOT resource [61_spot] +
* Target Disk(s) to install [select the empty disk]
DISK CACHE volume group name [] +
NIM IMAGE_DATA resource [] +
NIM BOSINST_DATA resource [] +
NIM EXCLUDE_FILES resource [] +
NIM INSTALLP_BUNDLE resource [] +
NIM PRE-MIGRATION SCRIPT resource [] +
NIM POST-MIGRATION SCRIPT resource [] +
Phase to execute [all] +
NFS mounting options []
Set Client bootlist to alternate disk? yes +
Reboot NIM Client when complete? no +
Verbose output? no +
Debug output? no +
ACCEPT new license agreements? yes +
, make sure you change the Accept new license agreement to yes.
It will 1st do an Alternate Disk Install and then it will do the migration.
Make sure you change the bootlist to new disk and reboot (after coordinating with other teams)
Hope this helps.