On Tue, Oct 18, 2011 at 7:18 PM, Edward Ned Harvey
<opensolarisisdeadlongliveopensola...@nedharvey.com> wrote:
> I recently put my first btrfs system into production.  Here are the
> similarities/differences I noticed different between btrfs and zfs:
> Differences:
> * Obviously, one is meant for linux and the other solaris (etc)
> * In btrfs, there is only raid1.  They don't have raid5, 6, etc yet.
> * In btrfs, snapshots are read-write.  Cannot be made read-only without
> quotas, which aren't implemented yet.

Minor correction: btrfs support ro snapshot. It's available on vanilla
linux, but IIRC it requires an (unofficial) updated btrfs-progs (which
basically tracks patches sent but not yet integrated to official
tree), but it works.

> * zfs supports quotas.  Also, by default creates snapshots read-only but
> could be made read-write by cloning.

There are proposed patches for btrfs quota support, but the kernel
part has not been accepted upstream.

> * In btrfs, there is no equivalent or alternative to "zfs send | zfs
> receive"

Planned. No actual working implementation yet.

> * In zfs, you have the hidden ".zfs" subdir that contains your snapshots.
> * In btrfs, your snapshots need to be mounted somewhere, inside the same
> filesystem.  So in btrfs, you do something like this...  Create a
> filesystem, then create a subvol called "@" and use it to store all your
> work.  Later when you create snapshots, you essentially duplicate that
> subvol "@2011-10-18-07-40-00" or something.

Yes. basically btrfs treats a subvolume and snapshot in the same way.

> * Both do compression.  By default zfs compression is fast but you could use
> zlib if you want.  By default btrfs uses zlib, but you could opt for fast if
> you want.

lzo is planned to be the default in the future.

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