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From: tli@sargas.usc.edu (Tony Li)
Newsgroups: comp.unix.wizards,comp.os.misc,comp.os.vms
Subject: Re: Uses for access time
Message-ID: <8726@oberon.USC.EDU>
Date: 26 Apr 88 08:13:42 GMT
References: <3672@lynx.UUCP>
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Reply-To: tli@sargas.usc.edu (Tony Li)
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Organization: University of Southern California, Los Angeles, CA
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In article <3672@lynx.UUCP> m5@lynx.UUCP (Mike McNally (Man from Mars)) writes:
    I am trying to convince some of my ``colleagues'' here that keeping track
    of last-access times of files is a useful pursuit for an operating system.
    The only good reasons I can come up with are
    
    1.	it's nice for accounting/housekeeping
    2.	it's a useful security feature (has anyone looked at my database 
    	since I left yesterday?)
    
Here's one example of #1 which I hope proves sufficient in and of
itself.

We keep a single pack here which we use to maintain sources for our
Unix system.  With comp.sources.misc, comp.sources.unix, alt.sources,
etc., this disk gets full rather rapidly.  By looking at the access
times, we can determine if a particular source file has been examined
recently.  If it has been touched 'recently', then someone has been
looking at it and we should probably leave it around.  Of course, this
is an implicit assumption of temporal locality.  If a file has not
been accessed recently, then it is probably not necessary in the near
future.  We can then either compress the file or archive it to tape.

I've seen similar schemes on Tops-20 which will archive a users files
in an attempt to minimize disk usage.

Tony Li - USC University Computing Services - Dain Bramaged.
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