OT - Scalable email server solution needed

Bill Moran wmoran at collaborativefusion.com
Sun Apr 9 14:55:53 UTC 2006

"Marc G. Fournier" <scrappy at hub.org> wrote:

> On Sat, 8 Apr 2006, Bill Moran wrote:
> > One advantage of Maildir over mbox and the Cyrus db (that, for some 
> > reason, I seldom see touted) is that you can make a safe backup of a 
> > Maildir without shutting down the SMTP, POP, or IMAP server.  With both 
> > mbox and the Cyrus mail system, you have to shut the mail system down to 
> > back up the mail boxes.
> Why with Cyrus IMAPd?  I just had a major hardware failure, had to restore 
> 30 mail spools from backup, all of which were 'backed up live', and the 
> only thing I had to do once restored was run the 'reconstruct' command to 
> make sure the various databases were sync'd up ... and the reconstruct 
> command can be run while the system is live too ...

I have only a small amount of experience with Cyrus.  However:

Based on that document, it appears as if you're dodging the bullet with
backups.  My interpretation is that Cyrus keeps mailboxes in some sort
of db file.  If a db file is being modified while you're backing it up,
the backed up version will be inconsistent, thus the entire mailbox

Compare this to Maildir, where each message is a seperate file.  If you're
backing up during access to a mailbox, a single message could end up
corrupt, but this will not affect the rest of the mailbox.

I set up backup for a Cyrus server for a client.  We've yet to have to
restore however, so all of my knowledge is based on that and other documents
on the web regarding Cyrus' operation.  It might be one of those things
where _theoretically_ the backups could be useless, but it almost never
happens in practice?

Bill Moran

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