For AIX:

mksysb (whithout map files - smitty mksysb) for rootvg
savevg (whithout map files for the other Volume Groups
smitty savevg)

For HP-UX:

ignite (make_tape_recovery _if the server has a tape_ or make_net_recovery _if you use an ignite server) for vg00.
vxdump to backup vxfs filesystems (see also: vxrestore).

Pay special attention when select a backup command, look for
large files aware backup commands and if you use UID's and GID's
larger than 60K.

For IRIX:

Idon't really know, but look at:

http://techpubs.sgi.com/library/tpl/...2.html#id48598

And follow the links of your interest.

Regards. Hugo.