I'm currently runing UW-IMAP (compiled vanilla) with procmail and mbox and am making my usual careful crawl (at turtle speed) through figuring out DC config. Some questions: a) I have something like 3-4 root imapd sessions so I presume that the default *login_processes_count* = 3 will be OK. I'm less clear about login_max_processes_count and login_max_connections = 256. A common enough heavy load has something like 275 unique users accessing imap and 600 imapd processes. Suggestions? I'm beginning with no SSL, KISS. b) If I set login_process_per_connection =no, would the number of users accessing imap be the same as the number of imapd sessions? c) login_process_size is confusing/intriguing. If there are 500 processes, the default of 32MB means 16GB (the box has 12GB). OTOH, what about the big players with a 400 MB inbox...will they be able to open their inbox with the default d) login_max_connections ditto...I shouldn't think that an individual user would conceivably have the default of 256, except pathologically....or is this applied to the listening imapd root processes. Thanks in advance for your help and patience......... -- ===Stewart Dean, Unix System Admin, Henderson Computer Resources Center of Bard College, Annandale-on-Hudson, New York 12504 sdean at bard.edu voice: 845-758-7475, fax: 845-758-7035
On Tue, 2007-03-06 at 16:05 -0500, Stewart Dean wrote:> I'm currently runing UW-IMAP (compiled vanilla) with procmail and mbox > and am making my usual careful crawl (at turtle speed) through figuring > out DC config. Some questions: > a) I have something like 3-4 root imapd sessions so I presume that the > default *login_processes_count* = 3 will be OK. I'm less clear about > login_max_processes_count and login_max_connections = 256. A common > enough heavy load has something like 275 unique users accessing imap and > 600 imapd processes. Suggestions? > I'm beginning with no SSL, KISS. > b) If I set login_process_per_connection =no, would the number of users > accessing imap be the same as the number of imapd sessions? > c) login_process_size is confusing/intriguing. If there are 500 > processes, the default of 32MB means 16GB (the box has 12GB). OTOH, > what about the big players with a 400 MB inbox...will they be able to > open their inbox with the default > d) login_max_connections ditto...I shouldn't think that an individual > user would conceivably have the default of 256, except > pathologically....or is this applied to the listening imapd root processes.I think you're misunderstanding all those settings and how the login processes work in general. Also I don't understand what you mean by "root imapd sessions". The login processes is handling the connection only before user has logged in. After login an imap process is started which does the mailbox opening and such. So login_process_size doesn't affect max. mailbox sizes. mail_process_size however does affect the max. mailbox size, but the default 256MB should be enough to handle hundreds of thousands of mails in a single mailbox. Also both of these specify the maximum allowed virtual process size, they don't really use that much memory to begin with. Their purpose is mostly to just avoid memory leaks from killing the machine. If you're not using SSL then after user has logged in, the login process knows nothing about the user anymore and it's free to serve another user. As long as you're not using SSL you could just leave all of them to defaults. Larger login_process_count means however that there are more processes available to handle the user logins, so if a lot of users are logging in at the same time a larger count would perform slightly faster than a lower count. I guess I should write about this to wiki. -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 189 bytes Desc: This is a digitally signed message part URL: <http://dovecot.org/pipermail/dovecot/attachments/20070307/ef219090/attachment.bin>
On 7 Mar 2007, at 16:21, Timo Sirainen wrote:> If you're not using SSL then after user has logged in, the login > process > knows nothing about the user anymore and it's free to serve another > user.And if you are using SSL? (Which, I'm sure, Stewart will get to in time)... If I remember other postings correctly then the login process does know something about the user: it acts as a proxy, passing data through from the IMAP client to the imap server process (and presumably back again?). Is that right? ... If so, then this was where the "Too many open files" problem arose in an earlier thread (the stdio library on Solaris defaulting to only allow 256 descriptors, or something). Like Stewart, I'm doing the slow turtle-speed crawl and don't have SSL in place yet. But when I get that far one of the things I have on my checklist is to verify I can open more than 256 SSL connections to the server at a time: potentially we'll need 1,000-2,000 at a time as use of IMAP over SSL increases. Cheers, Mike B-) -- The Computing Service, University of York, Heslington, York Yo10 5DD, UK Tel:+44-1904-433811 FAX:+44-1904-433740 * Unsolicited commercial e-mail is NOT welcome at this e-mail address. *