Endgame: Cyrus big install at UC Davis

[Bron Gondwana]

On Tue, 19 Feb 2008 12:50:09 -0800, "Vincent Fox" <vbfox at ucdavis.edu> said:
> So for those of you who recall back that far.....
> 
> UC Davis switched to Cyrus and as soon as fall quarter started
> and students started hitting our servers hard, they collapsed.
> Load would go up to what SEEMED to be (for a 32-core T2000)
> a moderate value of 5+ and then performance would fall off a cliff.
> People would be getting timed out, overall it was REALLY bad
> here for several days, lots of pressure....
> 
> We are running Solaris10 u4 and using a ZFS pool for the mail store.

Have you read this?

http://blogs.sun.com/roch/entry/when_to_and_not_to

I was forwarded there via:

http://rlwinm.blogspot.com/2007/10/my-parity-iz-pastede-on-yay.html

which I got to via a slashdot comment pointed out on a mailing list,
etc, etc.

Anyway, it looks quite interesting.  Thankfully our only use of ZFS
at the moment is the backup machine where each user's backup consists
of just two files (a sqlite DB and a .tar.gz).  I've already posted to
this list at length about how it works (very well, thankyou very much)
and the nice side effect that it detects file corruption automatically
by recalculating the GUID by doing a sha1 on the file as it goes into
the tar, so it can find any underlying issues in the cyrus spools.

Actually, every so often I'm tempted to turn the sqlite database back
into a flat file and gzip that as well - it would cost a bit more to
read, but the IO would _all_ be streaming then, and we have plenty of
memory.  We can still just append the changes.

Bron.
-- 
  Bron Gondwana
  brong at fastmail.fm