[Discuss] Discuss Digest, Vol 4, Issue 33

[richb at pioneer.ci.net (Rich Braun)]

Richard Pieri <richard.pieri at gmail.com> said:
>  LVM snapshots aren't filesystem
> snapshots like you get with AFS, ZFS and NetApp Filers.  LVM snapshots
> are block device snapshots that resemble AdvFS's transaction log mechanism.

I have two points to bring up before this well-flogged thread dies out:

1) 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.

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

Neither ZFS nor OCFS2 can compete for raw performance with ext4, which is a
remarkably well-optimized general purpose system.  But they do have some very
nice aspects.  (For example, with OCFS2 you can build a cluster:  multiple
servers attached to the same media via AoE/iSCSI or Infiniband switch.  That's
why I was looking at it.)

I know many folks do prefer to go with big commercial vendors.  But pretty
much everything that EMC, Netapp or Isilon do can be replicated with
open-source code.  It's not (yet) polished but those vendors do have to keep
innovating lest their bread and butter become a freely available commodity.  A
talented sysadmin with some well-crafted monitoring scripts can create a
carrier-class solution at a small fraction of the price, and it becomes
worthwhile to do if your deployment falls in a certain price range.

-rich