[tech] IMAP and NFS

[Michael Deegan]

On Sun, Aug 05, 2001 at 04:57:57PM +0800, Anil Sharma <Grand Poobah Maset> wrote:
> was reading some imapd docs, and they specifically stated not to use IMAP
> with NFS due to file locking problems (resulting in silently lost
> email).  Is this a problem with UCC atm?

I thought everyone knew that locking over NFS was horribly broken[1]? There
have been a couple of occasions where my UCC mail spool has been corrupted,
though my most recent case was probably an extreme one, due to fetchmail
polling via IMAP from home every five minutes, mutt polling via IMAP from
work every two seconds (oops, .muttrc specifies poll times in seconds, not
minutes! ;P). My work machine would cause fetchmail's IMAP connection to
die, usually in the middle of transferring mail, thus resulting in
duplicated mail. Although I haven't had any problems since setting polling
intervals to more sensible values, I don't think I should have had the
problems described.

I sent mail to wheel a few weeks ago, suggesting that perhaps rather than
run the IMAPd on mooneye, have it instead on morwong, and use port
forwarding so that non-WAIX users can get to their mail. I expect the same
thing should apply to POP, and perhaps even mail delivery, which would have
the side effect of relieving the distress inflicted upon mooneye by mailman.

HTH,HAND,

-MD

[1]: Mind you I don't know how much nfsv3 goes towards rectifying this. I
     appear to be successfully sharing my APT archive over my LAN[2] without
     apt-get complaining about (lack of) locking.

[2]: On the other hand, I am currently finding that if your export points
     are symlinks to subdirectories, then you should be very careful when
     you change the symlinks or remove the destination directory. I will
     have to reboot at some stage to get rid of a couple of duplicate
     /proc/fs/nfs/exports entries...

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Michael Deegan               Hugaholic               http://michael.ucc.asn.au/
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