Installed debian on a pair of Sun LX50 boxes and set up RAID1 in the process. Twice. The first try ended up totally dead and the second try sometimes hiccups at boot. There must be something I managed to mess up or something funny with the kernel that makes it sometimes refuse to start raid pairs.
Pretty nice machines all in all. SMP, serial redirected everything, very fast SCSI buses and quite nice construction in 1U. Heavy price tag though.
http://people.debian.org/~blade/install/ was a nice find.