----- Original Message ----- From: Christian Balzer [mailto:ch...@gol.com] To: dovecot@dovecot.org Cc: 24x7ser...@24x7server.net Sent: Fri, 10 Feb 2017 17:58:58 +0900 Subject:
On Fri, 10 Feb 2017 01:13:20 +0530 Rajesh M wrote: > hello > > could somebody with experience let me know the dovecot config file settings > to handle around 1500 simultaneous connections over pop3 and 1500 connection > over imap simultaneously. > Be very precise here, you expect to see 1500 as the result of "doveadm who |grep pop3 |wc -l"? Because that implies an ungodly number of POP3 connects per second, given the typically short duration of these. 1500 IMAP connections (note that frequently a client will have more than the INBOX open and thus have more than one session and thus process on the server) are a much easier proposition, provided they are of the typical long lasting type. So can you put a number to your expected logins per second (both protocols)? > my server > > server configuration > hex core processor, 16 gb ram 1 X 600 gb 15 k rpm for main drive and 2 X 2000 > gb hdd for data (No raid) > No RAID and no other replication like DRBD? Why would you even bother? How many users/mailboxes in total with what quota? 1500 IMAP sessions will eat up about 3GB alone. You will want more memory, simply to keep all relevant SLAB bits (inodes, dentries) in RAM. If you really have several hundreds logins/s, you're facing several bottlenecks: 1. Login processes themselves (easily fixed by high performance mode) 2. Auth processes (that will depend on your backends, method mostly) 3. Dovecot master process (spawning mail processes) The later is a single-threaded process, so it will benefit from a faster CPU core. It can be dramatically improved by enabling process re-usage, see: http://wiki.dovecot.org/PerformanceTuning However that also means more memory usage. Christian > > thanks > rajesh > [snip] -- Christian Balzer Network/Systems Engineer ch...@gol.com Global OnLine Japan/Rakuten Communications http://www.gol.com/ thanks christian during peak times here are the results for connections [root@ns1 domains]# doveadm who |grep imap |wc -l username # proto (pids) (ips) 631 [root@ns1 domains]# doveadm who |grep pop3 |wc -l username # proto (pids) (ips) 233 could you please guide me concerning the dovecot config files settings to handle the above 631 imap and 233 pop connections. number of mailboxes is around 4000 -- some users would consume 25 GB while others would be just around 10 MB this is a hex core machine with hyperthreading -- so 12 cores [root@ns1 domains]# iostat Linux 2.6.32-431.29.2.el6.x86_64 (ns1.bizmailserver.net) 02/10/2017 _x86_64_ (12 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 2.67 0.00 0.65 3.43 0.00 93.25 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdd 44.95 1094.25 765.10 720884842 504041712 sdc 1.92 32.15 0.03 21178186 21248 sdb 34.71 1377.37 625.54 907398402 412102224 sda 49.88 124.29 2587.32 81879548 1704506408 thanks rajesh
