On 02/19/2010 04:50 PM, Eric Luyten wrote: > On Tue, February 16, 2010 9:49 am, Eric Luyten wrote: > <...> >> ZFS is awesome. >> >> >> We have a ZFS pool composed of nine LUNs on an iSCSI-connected (2 x 1 Gbps) >> EMC Celerra. All disks are 7200 rpm S-ATA. >> >> >> On our previous storage system (FC-AL connected StorageTek with 15k and 10k >> rpm FC disks) I was able to run more finds/dumps/... in parallel without >> impacting mail service performance or message delivery rate. >> >> Even now I can pull close to 100 MB/s from the mail section of the storage >> subsystem without users noticing. 48 GB RAM on the mailserver sure helps, >> plenty of ARC :-) > > > (thought I'd share this with you lot :-) > > > Yesterday morning our mail server suffered a severe slowdown, leading to > hundreds of IMAP and POP clients hitting various timeouts, users getting > upset and starting to call helpdesks (offices down my hallway). > > All filesystems appeared sluggish at Solaris level while the iSCSI network > links and the SAN were only moderately loaded. Weird. > > Luckily I had recently read (on info-cyrus ? cannot find the article right > now) about a "ZFS> 80%" condition. I guess you are talking about: http://lists.andrew.cmu.edu/pipermail/info-cyrus/2010-January/032337.html > > Our Z pool was 83% full ... > Deleted the December snapshots, which brought that figure down to 74% > > Performance came right back :-) That's what we observed, it's sad because you virtually loose 20% of you capacity and if you have a multi-terabyte volume/pools it can be a lot! But since a lot of the IO is done on the meta data and the dbs in "configdirectory" (which is not very large) it helps to have them on volumes/pools separated from the imapspool. Didi ---- 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
