The ability to add new, differently sized disks with RAID-Z is the killer feature of ZFS. I wonder how Linux ZFS performance & stability compare with the FreeBSD ports? In the past, I've considered using something like FreeNAS for my home storage needs but the ZFS support wasn't ready last time I looked (1+ years ago?).
I also wonder the same. I was considering using BTRFS because it's better integrated, but if ZFS is more stable/mature, I'd go with that without even thinking. Has anyone used it for some amount of time?
I have used zfs-native on Ubuntu and Fedora a year or so ago for less than a month and found it to be unusable at best - I couldn't even copy my data from source to the backup ZFS disks - just went into a loop with high CPU. That may have changed a bit with later releases but I just don't think getting ZFS to scale and run reliably on different OS is going to happen anytime soon given how much effort and skills it would take.
What I am looking at doing is getting/building Solaris compatible box for my backup needs - that is a daunting task. But if I could do that I can run one of the OSS variants of Solaris - Joyent SmartOS, Nexenta etc..
I'm currently running a backup box nearly identical to the OP, and haven't had a problem yet (built it over a year ago). ZFS runs like a dream on Ubuntu, even with a slew of oddly sized disks (1TB + 2x2TB + 3TB) at 90% capacity. I've had my SATA card come loose, and ZFS just locks down the FS to r/o so no damage is done. And unlike many other file systems, ZFS's checking utility actually gives you human readable results if there is an error (eg. "/foo/bar is corrupt", not just cryptic messages), and outputs exactly what you should do to repair data.
I recommend at least trying ZFS out in a VM, I guarantee you'll be impressed by the versatility.
But know that to really use it, you want decent CPU speed, as much ECC ram as you can put in there, an SSD for cache (just one - doesn't have to match the raid size I don't think - it'l help a lot) and you still need to take into account all the normal raid cautious everyone ignores like rebuild times for 2TB sata2 drives -vs- failure rates, etc.... and if you want to use dedup without verify, that's your gamble.(smarter people than me say it's safe, but it just smells wrong)
