zfs discuss - Feb 2006 - Is there any work on making ZFS available on linux?

Hi ppl,

Just wanted to know whether any work is being done to make ZFS available on
Linux?

If yes is there any discussion forum for it.
What are the key areas to be addressed if zfs needs to be made available on
linux?

If not is there any idea in the future?

Regards
Ganesh
This message posted from opensolaris.org

On Sun, 26 Feb 2006, Ganesh Natarajan wrote:
> Just wanted to know whether any work is being done to make ZFS available on
Linux?
Correct me if I''m wrong, but the Linux kernel uses the GPL license,
which forbids the distribution of works that incorprate software
licensed under other licenses.  This means that a LInux distro that
includes ZFS code can''t be distributed (N.B., this is a limitation
of the GPL, not the CDDL), although the ideas behind ZFS could certainly
be icorporated into Linux.

But waering my SOlaris advocate''s hat, I say why bother?  IMHO, SOlaris
is way ahead of Linux (ZFS being but one example), so I''d use Solaris
if
at all possible.
> What are the key areas to be addressed if zfs needs to be made available on
linux?
The Linux kernel would have to be available under a CDDL-friendly license.

-- 
Rich Teer, SCNA, SCSA, OpenSolaris CAB member

President,
Rite Online Inc.

Voice: +1 (250) 979-1638
URL: http://www.rite-group.com/rich

First, one could use FUSE to avoid the license issue to a great
extent, but this would require a user-mode ZFS solution. Not optimal.

Second, one of the main ZFS advantages is that in many ways it mimics
WAFL (NetApp OS/Filesystem design) in that you have a tightly coupled
stack between software raid, volume management, and the filesystem. In
ZFS, it is hard to see where one ends and the next part begins. In the
Linux world, these are definitely separate. One of the big draws to me
with regard to ZFS on Solaris is a secondary effect of the
integration. Other than snapshots, I''d just be as happy with XFS for
many things, and currently it seems XFS is winning the NAS crown when
it comes to performance with NFS. However, the effect I''m speaking of
is that its integration solves other filesystem problems.

I need to leverage iscsi to constantly grow my storage pools. In the
Linux case, there is a very pronounced chicken-or-the-egg problems
with filesystems, software raid, and volume management when it comes
to iscsi and the network. The network comes up after local file
systems are mounted, but for every defined software raid array,
logical volume, etc that is iscsi-based, the system balks at those
during startup, either failing fsck on mount-at-boottime devices, or
later forcing full raid recoveries for later-arriving drives in an
array. Solaris w/ ZFS and its software initiator doesn''t have this
problem. Is its SVC? Is it their initiator? All told, its the
integration as this illustrates.

Bringing ZFS to Linux would likely require changes to sysvinit,
software raid in the kernel, logical volume management, etc along with
the addition of the filesystem. This is my new-to-ZFS understanding,
so treat it as such. However, I just don''t see it happening regardless
of license.


On 2/26/06, Rich Teer <rich.teer at rite-group.com>
wrote:
> On Sun, 26 Feb 2006, Ganesh Natarajan wrote:
>
> > Just wanted to know whether any work is being done to make ZFS
available on Linux?
>
> Correct me if I''m wrong, but the Linux kernel uses the GPL
license,
> which forbids the distribution of works that incorprate software
> licensed under other licenses.  This means that a LInux distro that
> includes ZFS code can''t be distributed (N.B., this is a limitation
> of the GPL, not the CDDL), although the ideas behind ZFS could certainly
> be icorporated into Linux.
>
> But waering my SOlaris advocate''s hat, I say why bother?  IMHO,
SOlaris
> is way ahead of Linux (ZFS being but one example), so I''d use
Solaris if
> at all possible.
>
> > What are the key areas to be addressed if zfs needs to be made
available on linux?
>
> The Linux kernel would have to be available under a CDDL-friendly license.
>
> --
> Rich Teer, SCNA, SCSA, OpenSolaris CAB member
>
> President,
> Rite Online Inc.
>
> Voice: +1 (250) 979-1638
> URL: http://www.rite-group.com/rich
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>

On Sun, 26 Feb 2006, Joe Little wrote:
> the addition of the filesystem. This is my new-to-ZFS understanding,
> so treat it as such. However, I just don''t see it happening
regardless
> of license.
Agreed.  If James Dickens'' adventures with Systemprobes (sp?) are
anything to go by, the Linux mob will try to reinvent ZFS--badly.

-- 
Rich Teer, SCNA, SCSA, OpenSolaris CAB member

President,
Rite Online Inc.

Voice: +1 (250) 979-1638
URL: http://www.rite-group.com/rich

Ganesh Natarajan wrote:

 > Just wanted to know whether any work is being done to make ZFS
 > available on Linux?

I''m interested in being involved in such a project in my spare time.  I
think the first step is to provide read-only support in Linux, which is 
quite possible using the on-disk format document which has been 
published.  A couple of months ago (during my Christmas holidays) I 
played around with some userland code until I got as far as reading data 
from a file in a ZFS filesystem.  I''ve started reading the linux kernel
code to figure out how to add a new filesystem, and the filesystem 
interface looks to be cleanly documented.

 > What are the key areas to be addressed if zfs needs to be made
 > available on linux?

Due to licensing incompatibilities, ZFS linux code needs to be written 
from scratch without reference to any opensolaris source code.  The 
on-disk format has been documented (with a few critical exceptions, such 
as the compression algorithm), but more documentation (or competing 
design work) would be needed to implement efficient write support.  I 
believe that it would be possible for a volunteer to produce such 
documentation by reading the opensolaris source code, so long as this 
volunteer did not write any ZFS linux code.

Rich Teer wrote:
> But wearing my Solaris advocate''s hat, I say why bother?  IMHO,
SOlaris
> is way ahead of Linux (ZFS being but one example), so I''d use
Solaris if
> at all possible.
Not only would this raise the profile of Solaris among Linux users, it 
would actually make it heaps easier for Linux users to try out 
dual-booting to Solaris on their PC.  Wouldn''t this be a positive thing
for Solaris advocacy?

Regards,
Luke.

> Second, one of the main ZFS advantages is that in many ways it mimics
> WAFL (NetApp OS/Filesystem design) in that you have a tightly coupled
> stack between software raid, volume management, and the filesystem.
Although WAFL only got this half right: they really didn''t integrate
the volume management part.  That''s why NetApp filers need NVRAM for
both performance and correctness, and ZFS doesn''t.  For details, see:

	http://blogs.sun.com/roller/page/bonwick?entry=raid_z

Jeff

Agreed. However, other differences make this up. They use RAID 4 and
raidgroups. Their advantage is that they got growable RAID arrays. I
hear this is coming to RAIDZ in the future :)

On 2/26/06, Jeff Bonwick <bonwick at zion.eng.sun.com>
wrote:
> > Second, one of the main ZFS advantages is that in many ways it mimics
> > WAFL (NetApp OS/Filesystem design) in that you have a tightly coupled
> > stack between software raid, volume management, and the filesystem.
>
> Although WAFL only got this half right: they really didn''t
integrate
> the volume management part.  That''s why NetApp filers need NVRAM
for
> both performance and correctness, and ZFS doesn''t.  For details,
see:
>
>         http://blogs.sun.com/roller/page/bonwick?entry=raid_z
>
> Jeff
>
>

I don''t think anyone''s working on it. The big issue is
incompatibility between the CDDL and GPL. Sun''s code can''t be
distributed with the official kernel. DragonFly BSD is planning to support ZFS,
however, which legally works because the CDDL is only viral at the file level
and the BSDL isn''t viral at all.
This message posted from opensolaris.org

off-topic: Is there a bug in the forum interface? I swear I didn''t see
the above replies before I posted.
This message posted from opensolaris.org