Cyrus imap server and filesystem type.

[Eric Luyten]

On Mon, October 3, 2011 11:13 pm, Pascal Gienger wrote:
> Le 03/10/2011 23:09, Vincent Fox a écrit :
>
>> On 10/03/2011 12:58 PM, Josef Karliak wrote:
>>
>>> Hi there,
>>> what filesystem type do you use for Cyrus imapd ? I use SLES11x64 (or
>>> opensuse 11.4). I use Reiserfs3.6, so far so good. But couldn't be better
>>> ? :)
>>>
>>
>> ZFS, which unfortunately is not much of an option for
>> you Linux folks I think.  ZFS works great with thousands of users, no worries
>> about getting "inodes" or partitions right and snapshots make keeping weeks
>> of recovery points online in the pool trivial and cheap
>
> I second this.
> Roughly 51,000,000 files on one (mirrored) multipathed FiberChannel SAN
> volume with no performance bottlenecks. 64 GB RAM per node, approx 40 GB ARC
> (ZFS Cache). Solaris 10u9   Kernel 147441-03   64bit x64


I third this.

45 million messages (down from 49M+ after summer cleanup) in nine filesystems
spread over four ZFS pools, attached to a single Solaris 10 server (dual quad
core Intel 2.8 GHz, although psrinfo reports 16 virtual processors, 72 GB RAM).

We keep in-spool daily snapshots for 120 days (adds roughly 50% used space).



One small remark : on occasions we have run in what apparently looks like a
ZFS bug and have been discussing this in private communication with a Oracle/
Sun performance specialist.

Details for Pascal and Vincent : at times (moderate to heavy I/O load) our
filesystem perfomance drops down to a very low level. Immediate relief can
be had by deleting a few ZFS snapshots and/or breaking one of more of the
mirrors.
Sounds, smells and feels like an allocation map issue, which is hinted at
in posts on a couple of OpenSolaris discussion forums.



Eric Luyten, Computing Centre VUB/ULB.