On Sat, Feb 25, 2012 at 3:52 PM, Richard Yao <r...@cs.stonybrook.edu> wrote: > ZFSOnLinux performance tuning is not a priority either, but there have > been a few patches and the performance is good. btrfs might one day > outperform ZFS in terms of single disk performance, assuming that it > does not already, but I question the usefulness of single disk > performance as a performance metric.
Why would btrfs be inferior to ZFS on multiple disks? I can't see how its architecture would do any worse, and the planned features are superior to ZFS (which isn't to say that ZFS can't improve either). Beyond the licensing issues ZFS also does not support reshaping of raid-z, which is the only n+1 redundancy solution it offers. Btrfs of course does not yet support n+1 at all aside from some experimental patches floating around, but it plans to support reshaping at some point in time. Of course, there is no reason you couldn't implement reshaping for ZFS, it just hasn't happened yet. Right now the competition for me is with ext4+lvm+mdraid. While I really would like to have COW soon, I doubt I'll implement anything that doesn't support reshaping as mdraid+lvm does. I do realize that you can add multiple raid-zs to a zpool, but that isn't quite enough. If I have 4x1TB disks I'd like to be able to add a single 1TB disk and end up with 5TB of space. I'd rather not have to find 3 more 1TB hard drives to hold the data on while I redo my raid and then try to somehow sell them again. Rich
