[OpenAFS] Replica sites

Russ Allbery rra@stanford.edu
Tue, 10 May 2005 11:39:12 -0700

ed <ed@ednevitible.co.uk> writes:

> Well, I like the features of AFS, however, the scenario is this, I have
> a single mail server for webmail, IMAP maildirs, spam filtering, virus
> scanning etc.

> This mailbox is getting loaded, primarily through IMAP access. I need to
> spread the IMAP folders out, so that one of 5 (more or less) front line
> mail servers can talk to one of a number of file servers.

> What software would your recommend for this?

While there are a few people who have had luck with smaller sites, the
common wisdom is that mail delivery into AFS will make you sad, if not
sooner than eventually.  Mail delivery does a lot of small file writes,
which is not AFS's best performance point, and AFS also has some
limitations in the number of files that can be put into a single directory
that are likely to cause problems for you if you really do have over a
million files in one directory.  (I'd worry about performance for
directory lookups there as well; AFS isn't as sophisticated as modern
local file systems in that regard.)

Personally, for an IMAP server, I would declare IMAP as the one and only
access mechanism to the data and then use local RAID storage on the
individual IMAP servers.  That's what we do at Stanford.

Russ Allbery (rra@stanford.edu)             <http://www.eyrie.org/~eagle/>