Are you using a ZFS or UFS file system? It makes a big difference. ZFS is definitely the way to go IMO, and the availability of a bootable ZFS root in OpenSolaris 2008.05 was the primary reason why I re-formatted my hard drive and re-installed everything.
If you're using ZFS, everything comes out of a pool and you can have different pools at different mount points and have different drives added and removed from different pools with a few commands at the command line. If you want to know what hard drives are currently attached to your system try typing in this command: pfexec format and then hit CTRL-C to exit out of it after you see the list of available drives. -- This message posted from opensolaris.org
