Subject: NFS problems WAS: Re: replacement for "filter"?

From: Raul Dias <[email-masked]>
Date: Wed, 8 Mar 2000 14:09:09 -0300

Hi,
	
>Because almost all user-access is now via POP or IMAP, there is only a
>small residual amount of file/NFS-based access.  (Yes, we know of the
>dangers of NFS which is why we have always deprecated it!)  We intend to
>remove this final file/NFS access, such as Elm, so that's OK for us (and
>we have warned the users!).

What are the dangers about using a NFS for mail spool? 
Where can I find more info about it?

Does it affect the HOME dirs? as /home is in a NFS server the 
$HOME/mail is affected to it (for local access)?

Thanks,

Raul Dias

---

From: David Lee <[email-masked]>
Date: Thu, 9 Mar 2000 14:02:01 +0000 (GMT)

> $HOME/mail is affected to it (for local access)?

The NFS comment was an aside in my original message (about filter
replacement).

Locking files via NFS is apparently fragile.  It is probably better on
recent releases of operating systems that it was a few years ago, but
should still be treated with caution.

Locking is, of course, vitally important on the spool file, when the mail
delivery program and the Mail User Agent (MUA) progam (Pine, Elm, ...)
might both try simultaneous writes to the file.  In the home directory
(for folders etc.), I still wouldn't be happy: suppose user had two MUAs
running? suppose there is a filter writing inbound email into the folder?

See "docs/locking.txt" in the IMAP distribution for more details.

My own view is that I won't trust NFS locking until I understand the
details in that document as they apply to us (all servers and all
clients).  And I don't yet understand it...!

Hope that helps.

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