Vincent Fox <vbfox@xxxxxxxxxxx> wrote: > This thought has occurred to me: > > ZFS prefers reads over writes in it's scheduling. > > I think you can see where I'm going with this. My WAG is something > related to Pascal's, namely latency. What if my write requests to > mailboxes.db > or deliver.db start getting stacked up, due to the favoritism shown to > reads? I got substantial benefits from setting compression=on and recordsize=32K on the filesystem where deliver.db resides. After talking with our SAN staff it showed up that storage was our problem - it has problems with concurrent write and read calls, the system won't answer read requests if the write channel is "full". I don't know whether it is a firmwire issue or a non-capability of the storage system. Lowering ZFS' recordsize and activating compression on that partition cut down i/o rate and things are going normal here again. Thanks to all who helped! Pascal PS: The mirror resilvering problem was a misconfiguration of a brocade switch... Sometimes you don't see the forest due to so many trees (german proverb, "Man sieht den Wald vor lauter Bäumen nicht")... ---- 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
