High availability email server...

rgraves rgraves at carleton.edu
Mon Jul 31 23:27:21 EDT 2006

> Kinda surprising, but it DOES have something to do with Cyrus.  Caspur
> did their case study on cluster filesystems with their e-mail environment.
> It used Cyrus IMAP and some kind of SMTP (I think it was Postfix or

Their paper talks about Maildir. If you connect to mailbox.caspur.it:993 
you'll see a Courier-IMAP greeting.

Maildir is specifically designed not to need anything more fine-grained 
than filesystem metadata-level locking. In theory, it's even NFSv2-safe, 
though user-visible performance on typical IMAP loads sucks (see recent 
Thunderbird rants, and double). Cyrus usually expects more advanced 
locking facilities, but it depends on db backend.

I obviously can't argue with your own positive experiences with Tru64 
clustering (as with other former DEC products, I've heard only good 
things about Tru64, except that it's been mismanaged and mismarketed 
into irrelevance), but those of us on crankier OSes need to worry about 
such things. Sendmail 8.12.5 release notes: "NOTE: Linux appears to have 
broken flock() again"; UW-IMAP FAQ 
http://www.washington.edu/imap/documentation/FAQ.html#6.11, etc.

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