How to disable NFS fnctl in /etc/fstab?

[Jeremy Chadwick]

On Fri, Sep 05, 2008 at 12:11:20AM +0800, Tim Chen wrote:
> By the way, since the machine is running as a mail server which
> install postfix,courier-imap, will it happen any kind of data
> corruption due to NFS fnctl lock disabled?

Regarding postfix, you will probably need dotlocking enabled during
mailbox delivery.

http://www.postfix.org/NFS_README.html

Regarding courier-imap (have you considered dovecot?), you might
want to see commit revision 1.4.3 to the Makefile, indicating fcntl is
required to build the port on an NFS mount, so fcntl is forced:

http://www.freebsd.org/cgi/cvsweb.cgi/ports/mail/courier-imap/Makefile

Be sure to look at line 65 of the Makefile.

Regarding courier-imap itself, I believe it can be configured to use
dotlocks, but I can't find any documentation on this (I'm searching
Google though).

Finally, this seems relevant (arguing "do not disable fcntl over NFS!"),
as something I happened to be reading earlier today; see "Why is NFS so
slow?":

http://www.fefe.de/muttfaq/faq.html#common-problems

Personally, I think you're asking for trouble disabling fcntl on NFS;
the fact you're having to (more or less) reverse-engineer all this
software to find out if it's compatible with that scenario is added
proof.  The fact you're doing this on a mail server running an MDA
is even more scary.

-- 
| Jeremy Chadwick                                jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |