Date: Sun, 9 Apr 2006 18:13:10 +0100 (BST) From: Jan Grant <jan.grant@bristol.ac.uk> To: Bill Moran <wmoran@collaborativefusion.com> Cc: "Marc G. Fournier" <scrappy@hub.org>, duane@greenmeadow.ca, freebsd-questions@freebsd.org Subject: Re: OT - Scalable email server solution needed Message-ID: <20060409180902.K97495@tribble.ilrt.bris.ac.uk> In-Reply-To: <20060409105550.0620530a.wmoran@collaborativefusion.com> References: <443731E5.9030209@greenmeadow.ca> <20060408074034.200f77a1.wmoran@collaborativefusion.com> <20060409002843.B1096@ganymede.hub.org> <20060409105550.0620530a.wmoran@collaborativefusion.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Sun, 9 Apr 2006, Bill Moran wrote: > 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. Not quite. Cyrus maps the imap hierarchy onto directories, with one (written once only) file per message. As flat-file as you can get. On top of this are per-folder index files (which can be recreated using reconstruct) holding stuff like preformatted IMAP responses, header indexes etc. That's where cyrus gets its speed from. Additionally there's a per-server "mailboxes" DB holding folder information (including ACLs), per-user seen/subscription databases and a deliverdb for duplicate suppression. The latter can all be stored in multiple formats, including bdb; hot backups for these work much the same way as for anything other bdb. It's not perfect, but there's minimal bullet-dodging. jan -- jan grant, ISYS, University of Bristol. http://www.bris.ac.uk/ Tel +44 (0)117 3317661 http://ioctl.org/jan/ ioctl(2): probably the coolest Unix system call in the world
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20060409180902.K97495>