OK this is something that has been confusing me for a little while and it's something I felt best to ask a place where I'm likely to find a definitive answer.

For a start, is the zeta file system in Snow Leopard or just in Snow Leopard Server?

And the second question is based on a theoretical plan I have. I'm going to get an external drive, 4-bay, with a 1TB drive per bay. Though by that time there's word that Seagate will have 2TB drives out. Either way, lots of storage. Before ZFS I had resigned myself to the fact I was going to have to get some sort of server setup since I needed RAID 5 support (mirroring of two stripped drives) but now it sounds as if ZFS can do all that for me but not in the same way that OS X would do with a software RAID. Do I have this completely wrong or is this actually something that ZFS can do for me?

I ask because it would mean instead of getting a lot of extra hardware I could get any 4-bay external enclosure that had the connections I wanted and then use ZFS to create a RAID-like drive.

And that leads me to my final question. For those of you who are more familiar with the way ZFS works, say I did do what I intended and created a 4-drive RAID-like setup where two drives mirrored the other two. How easy would it likely be to upgrade and swap out drives to add more space?

Any links to more information people can provide would be fantastic! I figure I should get planning now so that when this all happens I'll have the information I need to buy the right gear.