On Thu, 28 Feb 2008, Michael Bacon wrote: > I've never seen drbd used for Cyrus, but it looks like other folks have > done it. The combination of drbd+lvm2+ext3 might put you somewhere > unpleasant, but I'll have to let the Linux-heads jump in on that one. Don't try it with 4k stacks, IMO. It could blow up badly. Stacked devices and filesystems have this nasty tendency to eat up way too much stack :( And whatever you do, don't do mailspool IO patterns over Linux raid5 with the raid bitmap updates enabled and ext3. Performance goes to crap. I don't exactly know how to enable or disable these bitmaps, though. Look at mdadm's manpage. > > a linux software RAID 5 (3 SATA disks). On top of the md layer is the > > drbd device; on top of that is an lvm2 logical volume; on top of that is > > an ext3 filesystem, mounted > > as '/var/imap'. The mail is then in /var/imap/mail and the metadata in > > /var/imap/config (and we also have /var/imap/certs for the ssl stuff, and > > /var/imap/sieve for sieve scripts). Do look into that md raid bitmap option, remember that using lvm anywhere in a chain kills any and all write-barrier support which means a full sync-cache command to the HD even if it is a nice SCSI one, remember that drbd is not a lightning bolt either (you do have a direct gigabit ethernet link in use just for the drbd sync, don't you?), and remember to inform lvm AND ext3 of the raid stripe size when making the filesystems and lvm volumes. Also, the usual mount tricks like noatime should apply. -- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh ---- 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
