ZFS is a wet dream.
Once I saw this video, and tried the same thing for myself, I was hooked:
http://www.opensol...fs/demos/selfheal/ I've used it on Solaris 10, Solaris Express Developer's Edition (2/07), and OpenSolaris (B52?), but I don't have a linux system to test it on, or time to set one up right now.
Has anyone used it under FUSE, and how is it? Does it have automatic iSCSI target creation and such support under Linux?