Date: Tue, 14 Feb 2006 17:02:11 -0800 From: Bill Campbell <freebsd@celestial.com> To: freebsd@celestial.com, freebsd-questions@freebsd.org Subject: Re: Large imap server. Message-ID: <20060215010211.GB51548@alexis.mi.celestial.com> In-Reply-To: <cone.1139952830.347647.4979.5001@35st-server.simplicato.com> References: <20060207222202.GA8604@math.jussieu.fr> <43E9B39B.2070507@locolomo.org> <20060208170851.GA90120@alexis.mi.celestial.com> <cone.1139952830.347647.4979.5001@35st-server.simplicato.com>
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On Tue, Feb 14, 2006, Francisco Reyes wrote: >Bill Campbell writes: > >>Cyrus scaling? > > >We currently user Courier and so far I am far from impressed with it's >scalability. > >We have NFS servers for the storage and then front end machines for the >POP/IMAP connections. The footprint per connection is about 3MB to 5MB on >the client. On a machine with 2GB that means about 600 connections... but >the machines usually are dying around 400 connections. I'm looking at an ISP's server now with about 7,500 mailboxes with a load average about 0.29 using courier-imap to serve POP and IMAP clients. This server is answering about 4,800 courier connections per hour (mostly POP3). Granted that POP3 connections are typically very short duration compared to IMAP which may be open for extended periods of time. This server is the primary NFS server with 2GB of RAM, with dual 3GhZ Pentium IVs. While not a truly low-end box, it probably cost about $1,500USD. This system as one publically accessible MX server that handles all incoming messages, rejecting about a million connections using a combination of DNSRBLs and postfix rules. It runs all the incoming mail through with postfix, amavisd, and clamav, then passes messages that get through without virii or phishing to one of four boxes that use spamassassin to route spam into spam folders. We chose to run a single incoming MX server since the spammers would simply cycle amongst backup MX servers when rejected. These four boxes run with a load average about 3.0 or less, and have 1GB RAM on 2.66GhZ Celerons -- not exactly high-end boxes these days. The hardware cost of these machines is probably about $600USD each. Any or all of these machines could serve POP and IMAP as well, but we prefer to let them concentrate on spamassassin which is a true RAM hog. Adding capacity in this type of system is trivial, relatively inexpensive, and, other than the central NFS user store, not vulnerable to a single point of failure (each machine has its own openldap server for authentication which can be rebuilt from the master very easily, which can be required as the openldap doesn't respond well to unclean shutdowns). Bill -- INTERNET: bill@Celestial.COM Bill Campbell; Celestial Software LLC URL: http://www.celestial.com/ PO Box 820; 6641 E. Mercer Way FAX: (206) 232-9186 Mercer Island, WA 98040-0820; (206) 236-1676 http://www.celestial.com/ You need only reflect that one of the best ways to get yourself a reputation as a dangerous citizen these days is to go about repeating the very phrases which our founding fathers used in the struggle for independence. -- Charles A. Beard
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