[OpenAFS] Replica sites

[Robert Banz]

> 
> FYI, I'm running courier and using maildirs in the users's home
> directory for mail delivery.
> 
> That way you have 1 volume per user.
> 
> There are some gotchas, but I've been running this in a small
> environment for quite awhile now. I think this could be all cleaned up
> with a few patches to courier and some more robust AFS file access
> regression tests.  (delivering mail to maildirs and serving out imap is
> appently a good way to find race conditions in the afs kernel module)

The gotchas that I ran into never had anything to do (really) with AFS, 
but more to do with maildir's lack of any reasonable UID storage 
implementation, which lead me to do a lot of work on getting the 
c-client maildir stuff up-to-snuff for this.  Unfortunatly, it meant 
running afoul (in some ways) of the maildir "spec".  (not really a 
problem, since our only supported method of reading mail at our site is 
our imap & pop servers, or for the old-schoolers, our build of pine)

I'll offer it up to anyone that wants to play with it...
http://www.nofocus.org/wordpress/maildir/

I'll note that I spent quite a bit of time running this under 
strace/truss/whathaveyou to make expensive (FS access) syscalls as few 
as possible.

We currently use procmail for delivery, and recently realized that 
procmail was still trying to "lock" maildir mailboxes (this is version 
3.22).  These things are always fun:
http://www.umbc.edu/oit/sans/core/log/archives/2005/05/mail_problems_a.html

I should get that patch up when I get some free time.

-rob