[Discuss] ZFS

[tmetro-blu at vl.com (Tom Metro)]

Rich Braun wrote:
> ZFS kernel module for Linux is not an Oracle/Sun-sponsored product, so far
> as I can tell.  Lawrence Livermore Labs appears to be the current sponsor (see
> zfsonlinux.org) of the Linux upstream.  A firm in India called KQ Infotech
> pioneered this port but then got bought out by STEC earlier this year.

Ah, so this isn't the FUSE user-space driver we've heard about before,
but an actual kernel driver.

http://zfsonlinux.org/faq.html#WhatAboutTheLicensingIssue

  One way to resolve this issue is to implement ZFS in user space with
  FUSE where it is not considered a derived work of the kernel. This
  approach resolves the licensing issues but it has some technical
  drawbacks. There is another option though. The CDDL does not restrict
  modification and release of the ZFS source code which is publicly
  available as part of OpenSolaris. The ZFS code can be modified to
  build as a CDDL licensed kernel module which is not distributed as
  part of the Linux kernel. This makes a Native ZFS on Linux
  implementation possible if you are willing to download and build it
  yourself.

Interestingly the very next question directs Ubuntu users to a
repository of ready-built binary packages. :-)


> There is a snapshot-oriented filesystem project sponsored by Oracle: 
> OCFS2.  It's actually quite good.  I haven't looked at its snapshots yet.

What? Oracle wasn't busy enough developing Btrfs? They had to create
another one? :-)

I see the focus of OCFS2 is clustering, which is not necessarily the
case for Btrfs. There doesn't seem to be a leading choice for clustering
file systems for Linux. Plenty of options, but no clear leader.


> Neither ZFS nor OCFS2 can compete for raw performance with ext4...

Reference?

One data point is:
http://zfsonlinux.org/faq.html#PerformanceConsideration

"...it should be made clear that the ZFS on Linux implementation has not
yet been optimized for performance..."

Of course performance is relative. If you are building a 4-drive NAS for
a SOHO application, the performance difference between ZFS and Ext4 may
be indistinguishable (or not? need to see some benchmarks), or at least
a justified cost for a more self-maintaining storage appliance.

 -Tom

-- 
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/