[OpenAFS] Overview? Linux filesystem choices

Jeffrey Altman jaltman@secure-endpoints.com
Wed, 29 Sep 2010 16:18:31 -0400

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On 9/29/2010 12:28 PM, Stephan Wiesand wrote:
> On Sep 29, 2010, at 17:49 , Harald Barth wrote:
>> Currently our AFS servers are on Linux and XFS. We were thinking of
>> moving to OpenSolaris or Solaris and ZFS. But as things are now, these=

>> options either have a very unsecure future or a very hefty pricetag.
>> For us, the name change of the company did result in a doubling of
>> prices, something that we did not pay but took another solution. I am
>> still searching for a good software raid solution. Any experiences
>> with ZFS on FreeBSD out there? Other suggestions?
> Well, how about hardware RAID? The only flavour I have recent first han=
d experience with are the LSI Megaraid Controllers (or, more precisely, O=
EM controllers based on them from our current main hardware vendor): They=
 do RAID-6 at reasonable speed, scrub the disks and check the parity acco=
rding to your needs, keep a log of drive problems and error counters inde=
pendent of the OS, come with a BBU option, and are reasonably cheap. They=
 isolate you from having to deal with SATA drives or baseboard chipsets. =
And they have a *stable* management interface with a lean CLI for accessi=
ng it independent of vendors' management suites.
> While I had loved to see ZFS for Linux (and am still hoping for it, or =
for btrfs becoming production grade), we have been quite happy with this =
solution (and are now runnig ~ 1.5 PB of disk storage this way). We're us=
ing ext3 on top for vicep partitions, but XFS is doing well on other (non=
-AFS) fileservers here and we'd use it for AFS if it had serious advantag=
es for our use case. IMO, XFS is just slightly more adventouros.

RAID is not a replacement for ZFS.  ZRAID-3 protects against single bit
disk corruption errors that RAID cannot.  Only ZFS stores a checksum of
the data as part of each block and verifies it before delivering the
data to the application.  If the checksum fails and there are replicas,
ZFS will read the data from another copy and fixup the damaged version.
That is what makes ZFS so special and so valuable.  If you have data
that must be correct, you want ZFS.

Jeffrey Altman

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