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Date:      Thu, 19 Dec 1996 14:26:41 +0100 (GMT+0100)
From:      af@biomath.jussieu.fr (Alain FAUCONNET)
To:        ttsai@pobox.com
Cc:        questions@freebsd.org
Subject:   Re: Freebsd for mail/shell server
Message-ID:  <199612191326.AA03396@iaka.biomath.jussieu.fr>
In-Reply-To: <199612191159.FAA25460@edison.ebicom.net> from Tim Tsai at "Dec 19, 96 05:59:04 am"

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Tim Tsai wrote / a ecrit:

>   Is anybody running FreeBSD with the mail directory mounted from
> another machine?  If so, how do you keep from corrupting the mailboxes
> if NFS locking is not supported?

I have FreeBSD, Ultrix, HP-UX, SunOS, Solaris, AIX and NeXTstep  boxes
with their mail spools NFS mounted for a HP-UX server. Corruption  has
occured only a couple times in 5 years, and the culprit most  probably
was the pop daemon.

NFS  locking  is  not supported on some of the above machines (FreeBSD
among   them).   On  other  machines  (AIX  and  NeXTstep)  it   seems
hopelessly broken.

> 
>   I want to support shell users but I would rather not have mail be on
> the same machine.  Ideally I would have a dedicated mail machine and NFS
> mount the mail directory on the shell machine.  Could this work?

Yes.
My  rule  is  to  use *only* mail user agents and mail delivery agents
that  use  and  understand  the most basic locking mechanism: dot file
locking   i.e.   creation  of  a  /var/spool/mail/joe.lock  file  when
/var/spool/mail/joe is being accessed. Most mail user  agents  support
that,  including elm if compiled with the proper options. My mail host
is a HP-UX box whose mail delivery agent is  procmail.  Procmail  does
support  dot  file  locking.  I had to modify Qualcomm's POP daemon to
plug in dot file locking (just doing it for qpopper v2.2 right now).

Hint: given a mail user agent program, either check the sources or try:

strings [-a] binaryfile | grep \\.lock

To check if it understands dot file  locking.  If  you  get  "%s.lock"
somewhere,  chances are good that it does.

_Alain_


-- 
Alain FAUCONNET    Ingenieur systeme - System Manager     AP-HP/SIM
Public Health                91 bld de l'Hopital 75013 PARIS FRANCE
Medical Computing Research Labs         Mail: af@biomath.jussieu.fr
Tel: (+33) (0)1-40-77-96-19             Fax: (+33) (0)1-45-86-80-68
    I've RTFMed. It says: "Refer to your system administrator"
            But... I *am* the system administrator :-]



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