Comment Re:Why ext4 (Score 1) 226
Agree, as the other reply pointed out as well. And you can do the same with mdadm raid too (though obviously with none of the benefits btrfs/zfs bring for data integrity like checksumming and copy-on-write). Mdadm will also let you reshape an array in place (that is change raid levels or number of disks), though with mdadm that will often result in messing up your stripe alignment and of course it is more likely to eat your data if something goes wrong since if it finds a parity mismatch it has no way to know which copy is bad.
I was just commenting that btrfs tends to have a lot of features that appeal to small system users that you'll actually find missing on zfs, even if it is far less mature overall, and lacking in many enterprise-scale features. It just reflects the emphasis of the developers behind it.
I really can't complain about zfs - it is a great filesystem. However, things like not being able to reshape an array or mix disk sizes in an array are some of the things that hold me back from adopting it. Heck, btrfs will let you switch from raid1 to raid5 without touching any of the data already written - newly-allocated chunks will use raid5 and existing chunks will continue to use raid1 - it doesn't manage arrays at the whole-device level. In practice though you're likely to tell it to rebalance your data of course.