----- Original Message ----- From: "Russell Coker" <[EMAIL PROTECTED]> To: "Colin Ellis" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Monday, February 24, 2003 7:16 PM Subject: Re: Mail server > > If a message delivery takes 10 disk writes (actually it probably takes more > once you count writing to two files in the queue then writing it to the spool > and deleting the queue files with lots of fsync() along the way) then such a > machine can only deliver 13 messages per second. > > I'm running a number of mail servers with lots of spare disk space that are > hitting the message delivery limits, which prevents me adding more users. >
I totally agree with Russel; disk speed is probably the most important limiting factor, not CPU speed or diskspace. To add some more numbers: I've just been doing some benchmarks to test different filesystem/mailserver combinations, testing with Russel's excellent Postal benchmark program. The best result on our testmachine (celeron 1700, 256 megs of RAM, 80 GB 7200 rpm IDE disk) have been a constant 30-35 messages per second. This was with a combination of XFS, Exim and Maildir storage, and with a maximum message size of 10K. A more realistic 100K maximum size still resulted in about 20-25 deliveries per second. These numbers are, however, only for mail delivery using SMTP; retrieving the mail using either POP or IMAP will add significant load. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]