[OpenAFS] zfs File system

Brian Sebby sebby@anl.gov
Mon, 21 Apr 2008 18:19:20 -0500

This seems to have been discussed quite a bit already, but we also moved
our fileservers from inode to namei on ZFS in Solaris.  Fortunately, this
was part of a hardware upgrade, so all I had to do was set up the new
file servers using ZFS, and use vos move to move over the volumes.  Once
it was done, I just shut down the inode file servers.  As others have
mentioned, running on inode these days is asking for trouble - Sun has
made a number of changes to the UFS file system in the past couple of years,
and several of them have broken AFS.

It's worked really well for us.  I haven't noticed any significant 
performance hits, but I don't know how much of the gains we've seen are
due to ZFS/namei and which are due to simply being on faster and more
modern hardware.

We currently have two types of ZFS /vice partitions: one server has locally
attached disks that are combined in a RAID-Z2 (RAID 6) configuration, while
the others are concatenation devices, with the "single" device the servers
see actually being configured in a RAID-6 configuration on our SAN.  All
are using ZFS, and work well.

You may need to do a little tuning of the ZFS Adaptive Replacement Cache
to make sure it doesn't gobble up all of your memory, and you should make
sure to turn off atime on the ZFS pool as well as changing the block size
to 64k.

I highly recommend reading through Dale Ghent's presentation about using
AFS with ZFS and Zones from last year's OpenAFS Workshop.  That helped
me a lot when I migrated our AFS infrastructure to Solaris 10.  The only
caveat I wanted to mention is that the method of tuning the ZFS ARC has
changed since last year; at that time, you had to manually tweak the
kernel, but it's now an /etc/system parameter.


On Mon, Apr 21, 2008 at 01:43:12PM -0400, Prasun Gupta wrote:
> On solaris the recommended filesystem of use for building afs filesystem
> is ufs without logging turned on. This is really a very primitive file
> system, and it loses a lot of the new features in the filesystems.
> Has anybody used zfs successfully and in what configuration ?
> a)       striped zfs
> b)       Raid5 zraid1 zfs
> c)       Raid6 zraid2 zfs
> Any recommendations will be greatly appreciated ?
> Thanks
> Prasun

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