OT - Scalable email server solution needed

Marc G. Fournier scrappy at hub.org
Sun Apr 9 22:52:47 UTC 2006

On Sun, 9 Apr 2006, Bill Moran wrote:

> "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:
> http://cyrusimap.web.cmu.edu/twiki/bin/view/Cyrus/Backup
> 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
> unusable.

Agreed, but this db file is stored within the maibox itself, and which is 
what Cyrus has a 'reconstruct' command to rebuild ... so, after a restore, 
the first thing you run in 'reconstruct' to make sure you database(s) 
match the 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.

Oh, wait, I misunderstood your first paragraph ... Cyrus IMAP stores its 
individual mail messages in a seperate file (old 'mh' kinda thing), but 
there is a db file that maintains the 'state' informatin for the folder 
(what messages have been read, marked deleted but not purged, etc) ...

Marc G. Fournier           Hub.Org Networking Services (http://www.hub.org)
Email: scrappy at hub.org           Yahoo!: yscrappy              ICQ: 7615664

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