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Building a Scalable Mail System?

Posted by ryuzaki0 on from the multiple-mail-servers dept.

clusteredMail asks: "I work for a small ISP that up until now has survived with single servers for most critical roles, including the mail server. We are planning to introduce multiple mail servers (primarily for email collection via POP3 and IMAP) and want to put in place the most scalable, resistant to failure system that we can manage. Everything is currently running on one or another flavour of Linux. In my mind, the ultimate scenario would be to have some sort of distributed/clustered file system between the multiple machines, so that any user could log onto any server, and the loss of a single server would not cause downtime for any group of users. Has anyone in the Slashdot community had to put together a system like this using Linux and Open Source Software? If so, how did you fare and what were the major stumbling blocks?" "So far, the plan is to split up the mail accounts between multiple servers and use some sort of connection proxy to sort out which account logs into which server but this seems like a rough approach. The disadvantage to this setup: if one server fails all the users who have accounts on that machine will be in the dark, email-wise."

2 of 109 comments (clear)

  1. I am in the process of doing this... by charlesnw · · Score: 3, Interesting

    I run an open source project that is building an exchange replacement. http://www.thewybles.com/~charles/oser is the project homepage. It will be highly available (supporting both hardware (cisco/webmux load balancers) and software based load balancing. Along with a whole host of other groupware functionality. I have done high availability e-mail solution deployments. I am in the SoCal area but am willing to travel if necessary. There are others who can help you as well. Your choice. My blog covers a lot of the progress of the project and details. I would be happy to work with you to complete this task. Just e-mail me and we can work out an arrangement.

    --
    Charles Wyble System Engineer
  2. Re:Check out Perdition by Bronster · · Score: 3, Interesting

    Alternatively, check out nginx. Sure you have to wade through the Russian, but the configuration syntax is pretty simple and it's easy enough to build.

    It uses epoll. We replaced a perdition proxy that was seriously loading two servers with a single 8 process nginx instance that's not even breaking a sweat. It's amazing what the change from 32000 process down to 8 processes can do on a busy site! The two frontend machines are now configured with heartbeat to get full failover of IP addresses. Downtime appears to be on the order of 1-2 seconds with an orderly cutover and probably about 10 seconds for a total host failure.

    Cyrus supports replication now, which is a good way to handle the backends. I'd say more about it, but I haven't actually finished configuring the full failover system yet for this - lots of gating logic required to make sure two machines don't both believe they're master for a bit!

    Er, but why would I help you anyway, you're the competition ;)

    (I work for FastMail.FM btw)