ZFS and Deduplication?

[Xin LI]

Hi, Steve,

On Wed, Mar 24, 2010 at 10:24 AM, Steve Pate <spate at mac.com> wrote:
> I'm really not familiar with the FreeBSD development process so I apologize if I'm asking questions which appear naive.
>
> We'd like to ship a FreeBSD-based product by early next year that contains ZFS with de-dup. From what I see, FreeBSD seems to be tracking Solaris in terms of taking stable versions of ZFS. In other words, you're taking the version of ZFS that will next move from Open Solaris to Solaris. Is that correct?
>
> >From what I understand FreeBSD 8-STABLE includes ZFS version 14, which brings it to parity with Solaris 10.
>
> ZFS version 21 contains de-duplication so is quite a long way ahead of where FreeBSD is today. This implies that it will take quite some time for ZFS + de-dupe to get into a stable version of FreeBSD. Correct?
>
> Now, if we were to port ZFS version 22 (or later) to FreeBSD 8.x (version number TBD), how could we work with the FreeBSD team to get ZFS version 21+ back into a subsequent FreeBSD release?

Pawel is working on porting the -HEAD ZFS version from OpenSolaris right now.

For FreeBSD 8.x I think there are some things that we need to take
into consideration.  OpenSolaris generally strives to keep API/ABI
stability but for ZFS management tools like zfs(1m) and friends this
does not apply, e.g., the ioctl request structure changes from time to
time.

In the past we broke ABI across ZFS v6 -> v13 update.  This basically
means one will have to update kernel and userland at the same time,
which would make the upgrade an one-way ticket (otherwise it would be
impossible to do operations like zpool import once kernel is upgraded
and restarted).  I think, if we plan to MFC it we need to make some
compatibility shims instead of using the current approach.

Cheers,
-- 
Xin LI <delphij at delphij.net> http://www.delphij.net