From owner-freebsd-doc  Wed Sep 19 20: 0:10 2001
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Date: Wed, 19 Sep 2001 20:00:03 -0700 (PDT)
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From: "Eugene M. Kim" <gene@nttmcl.com>
Subject: Re: docs/30675: `noatime' should be discouraged on /var as well
Reply-To: "Eugene M. Kim" <gene@nttmcl.com>
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The following reply was made to PR docs/30675; it has been noted by GNATS.

From: "Eugene M. Kim" <gene@nttmcl.com>
To: Chern Lee <chern@FreeBSD.org>
Cc: "Eugene M. Kim" <gene@nttmcl.com>,
	freebsd-gnats-submit@FreeBSD.org
Subject: Re: docs/30675: `noatime' should be discouraged on /var as well
Date: Wed, 19 Sep 2001 19:55:41 -0700

 Chern,
 
 Your observation is correct.  Sendmail does not explicitly manipulate
 the mtime nor the atime.
 
 What happens is, when sendmail has something to deliver to a mailbox, it
 just opens the mailbox file as write-only.  This operation updates only
 the mtime of the mailbox, and its atime is preserved.  Result: the
 mailbox now has an mtime more recent than its atime, which is the
 indication of new mail.
 
 See also tcsh(1), under the description of `mail' variable.
 
 Regards,
 Eugene
 
 A mail-reader resets that condition by reading from the mailbox.  
 On Wed, Sep 19, 2001 at 05:52:32PM -0700, Chern Lee wrote:
 > A quick grep -Ri "atime" /usr/src/contrib/sendmail/ shows that sendmail
 > does not use file atime's for any operations.  Mail program often use
 > *modification timestamps* (mtime), which is not changed by the noatime
 > option.
 > 
 > Generally speaking, mtime is updated every time a file's contents is
 > changed, atime is changed whenever a file is accessed.
 > 
 > If my memory serves me correctly, postfix does not make use of atime
 > either--I safely run a postfix server with noatime enabled on /var.
 > 
 > - chern
 > 
 > 

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