[OpenAFS-devel] Re: afscache on UFS+logging or ZFS?

[Andrew Deason]

On Tue, 03 Aug 2010 22:36:31 +0100
Robert Milkowski <milek@task.gda.pl> wrote:

> Hi,

Just by the way, these kinds of questions are more suited to
openafs-info than openafs-devel, I think.

> Can AFS cache be placed on any local filesystem like ZFS, VxFS or 
> UFS+logging?

ZFS and UFS have been used (with and without logging). I'm not sure if
anyone has tried to use VxFS, but in theory I think it should work as
our cache I/O mechanisms are supposed to be FS-agnostic.

Note that there is a known (unfixable) issue with ZFS caches that can
cause them to take up far more disk space than you have configured.
<http://www.openafs.org/pipermail/openafs-devel/2009-September/017033.html>
has some information. Decreasing the ZFS recordsize makes it not as bad,
though the issue is still always there.

You can still have a UFS cache partition easily on an otherwise-ZFS-y
system, though. Just make a zvol block device and create a UFS
filesystem on that.

> When I start afsd with a cache configured on UFS with logging it prints 
> a warning (see below) but otherwise seems to be working fine. It also 
> seems to be working fine over ZFS.
> It looks like it the below code is just a left-over and needs to be 
> removed... ???

As far as I know, this warning is still valid. The original reason for
that came from this, I think:
<http://www.openafs.org/pipermail/openafs-devel/2002-November/008646.html>
and I don't recall anyone doing anything to try to fix or work around
it.

-- 
Andrew Deason
adeason@sinenomine.net