> > I had the feeling whatever optimizations done at the FS level would give > > us a max of 5-10% benefit. > > We migrated from ext3 to reiserfs on our cyrus servers with 30k > > mailboxes. I am not sure I saw a great benefit in terms of the iowait. > > At peak times I always see a iowait of 40-60% > To be honest, that's not what we saw in our ext3 <-> reiserfs tests. > What mount options are you using? Are you using the mount options I > mentioned? > noatime,nodiratime,notail,data=ordered FYI, noatime implies nodiratime. You can set nodiratime without atime, but not atime without nodiratime. > > But the new Solid-State-Disks seem very promising. They are claimed to > > give 30x the throughput of a 15k rpm disk. If IO improves by 30 times > > that should make all these optimizations unnecessary. > > As my boss used to tell me ... Good hardware always compensates for > > not-so-good software. > What we've found is that the meta-data (eg mailbox.db, seen db's, quota > files, cyrus.* files) use WAY more IO than the email data, but only use > 1/20th the space. Ditto. The meta-data is very much the hot-spot for I/O. > By separating the meta data onto RAID1 10k/15k RPM drives, and the email > data onto RAID5/6 7.2k RPM drives, you can get a good balance of > space/speed. Agree. ---- 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
