--On Friday, November 16, 2007 7:39 AM +0100 Pascal Gienger <Pascal.Gienger@xxxxxxxxxxxxxxx> wrote: > Solaris 10 does this in my case. Via dtrace you'll see that open() on the > mailboxes.db and read-calls do not exceed microsecond ranges. > mailboxes.db is not the problem here. It is entirely cached and rarely > written (creating, deleting and moving a mailbox). This is where I think the actual user count may really influence this behavior. On our system, during heavy times, we can see writes to the mailboxes file separated by no more than 5-10 seconds. If you're constantly freezing all cyrus processes for the duration of those writes, and those writes are taking any appreciable time at all, you're going to have a stuttering server with big load averages. Again, it's not I/O throughput to be worried about here -- it's latency. If you don't have write caches in front of your disk, even with RAID you're still at the mercy of drive latency in the millisecond range. Not a problem if those writes are once every five minutes, but if you're at peak load on a big system and seeing them every couple of seconds, that's brutal. -Michael ---- Cyrus Home Page: http://cyrusimap.web.cmu.edu/ Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
