Date: Mon, 21 Jun 2004 20:32:45 -0400 From: Bill Moran <wmoran@potentialtech.com> To: Chuck Swiger <cswiger@mac.com> Cc: questions@freebsd.org Subject: Re: What's the best possible email failover solution Message-ID: <20040621203245.1f0e7444.wmoran@potentialtech.com> In-Reply-To: <40D76DA3.9090809@mac.com> References: <20040621132006.2b1a296f.wmoran@potentialtech.com> <a22ff294040621115173bad2e0@mail.gmail.com> <20040621172520.3544d6fe.wmoran@potentialtech.com> <20040621214348.GB63857@happy-idiot-talk.infracaninophile.co.uk> <20040621175626.3e762448.wmoran@potentialtech.com> <40D76DA3.9090809@mac.com>
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Chuck Swiger <cswiger@mac.com> wrote: > Bill Moran wrote: > > It's the mailboxes themselves that are difficult to get. Best we've got right > > now is backing up the Cyrus mail folders using rsync ... but this is very time- > > consuming, and (thus) only done once a day. In order for it to be done right, > > Cyrus has to be shut down while it's backing up. > > Are you using mbox files rather than maildir-style mailboxes? No, I'm using Cyrus' native storage method. I don't quite understand the details of how it lays things out, but it seems to create a number of files for each folder, although not quite 1 per message. > The latter uses one-message-per-file, and ought to work *much* better both in > terms of performance and stability, and in terms of playing nice with the way > rsync wants to back things up. Doesn't really matter. Fact is, the mail directories are something on the order of 3G. No matter how efficiently I store them, rsync is not going to be able to back them up fast enough to hit the level of redundancy I'm shooting for. Although Maildirs might work a little better, since I wouldn't have to stop the IMAP server during backup. It takes about 30 minutes to rsync the system to the backup server right now. That's perfectly acceptable for nightly backup purposes. This is a 1.5Ghz with 256M RAM and 80G ATA 100 HDDs. If the system runs rysnc continuously 24/7, I still have 30mins old data. > [ I don't think that stuffing email into a database is a particularly good > idea since that means keeping large blobs of non-relational data floating > around, something that the filesystem can do a better job of handling... ] It's a good idea if I want real-time redundancy. I see where you're coming from, and it's true that a RDBMS isn't the best way to store emails. But, when you look at the features available, it's the best way for this circumstance. With something like Slony, I'd have real-time redundancy with (I'm expecting) only a minor performance drop. Although I can't be sure until I can put something together to test. Reliability is much more important than performance in this case. Who cares if their email takes and extra 60 seconds to deliver, as long as it doesn't get lost! If the email arrives fast, it's useless if the server fails and the email is lost because the SMTP server told the delivering server that it had arrived and then crashed before it could be backed up. -- Bill Moran Potential Technologies http://www.potentialtech.com
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