How to reduce a logical volume on AIX
From MyWiki
AIX logical volume reduction procedure.
1. Export all volume groups except for rootvg
exportvg VGDATA
2. Set tape device block size to 512
chdev -l rmt0 -a block=512 -T
3. Create a rootvg backup using mksysb
mksysb -i /dev/rmt0
4. Reboot the system from CDROM
5. From the "Welcome to Base Operating System Installation and Maintenance" choose "Change/Show Installation Settings" and "Install"
6. Toggle the "Shrink File System" to YES. You will then be prompted to select a new size. (Make sure you leave enough space to restore your mksysb image)
7. Insert the mksysb backup tape and select "Continue with choices indicated above"
9. Reboot the system and import all exported volume groups
importvg VGDATA