Chad M Stewart <[email protected]> wrote: > Dovecot 2.2.18 on CentOS 6 > > I have a pair of servers setup with MySQL, Postfix, and Dovecot. Replication > is setup and working between the two dovecot instances. > > The problem I'm running into is that a single mailbox receives a lot > of messages, at times the rate is multiple messages per > second. Delivery from Postfix to Dovecot is via tcp based LMTP. When > I do 'ps -aef|grep lmtp|wc -l' I get 62 and does not appear to go > higher than that. At the moment I have 4500 and 8300 messages queued > on two Postfix instances waiting to deliver via LMTP to the same > dovecot instance. Deliveries only happen via LMTP and only one of the > two nodes actually gets the deliveries. > > What I'm seeing is very high load on the system (40) and queues > building on the Postfix side. Replication is keeping up. Looking at > the logs now I see anywhere from 4-7 messages per second delivered to > this single mailbox. I would like to increase that rate a lot. > > These machines are VMs hosted on Xenserver 6.x. I have them setup > with 8 vCPUs (2 sockets with 4 cores per socket), the dom0 machines > have dual HBA connectors back to a SAN and have 128 CPUs and 256GB of > RAM and are not taxed. I added a 2nd virtual disk that is used for > storing mailbox data. It is ext4 and has noatime set during > mount. /var is also mounted with noatime. > > The performance graphs in XenCenter show nearly all 8 vCPUs at about > 50%, and the writes on the mailbox data disk are about 20%. iostat is > showing mostly <5 for await times for the disks, though I do see a 10 > now and again. > > > I'm guessing that maybe I'm hitting a mailbox locking issue and not sure how > to reduce the contention and thereby increase the delivery rate to this > mailbox.
Could you provide the following info: a) mailbox type (maildir/mbox/dbox/...) [mail_location in dovecot's config] b) file system type (ext2/ext3/ext4/fat32/...) [provided by "df -T" command on my system] -- A. Filip
