SUMMARY: problem with Defragcron , Tru64 4.0G & dev/null

From: Alaric Turner (a.turner_at_albourne.com)
Date: 12/15/03

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    Date: Mon, 15 Dec 2003 17:18:03 +0000
To: tru64-unix-managers@ornl.gov

    Many Thanks to those that replied,
    as ever Dr Blinn of HP came up trumps,

    basically the problem was that a change has been made in defragcron
    (possibly in Patchkit 4)such that it deleted /dev/null every time it ran.
    alaric

    Dr Blinns' reply in full:

    >That's bizarre. I run V4.0G but I disabled defragcron long ago.
    >
    >It's a shell script; go see if you can spot a point where it does
    >an "rm -f" or whatever on /dev/null. A privileged user (and you have
    >to be running as root to run defragcron) has sufficient privilege to
    >remove /dev/null and if the device name is then used as the output
    >from some command invocation, it will be recreated as a "normal" file.
    >
    >I see in the version of the script in the patch kit output area this
    >stuff:
    >
    > quiet_file="/dev/null"
    >
    > /bin/rm "$quiet_file"
    >
    >and if you are root and that quiet_file is "/dev/null" and you do that
    >/bin/rm then /dev/null is GONE. This was NOT in the original version
    >of the script, someone put it in there as a "maintenance fix". Do
    >not run defragcron, it's dangerous anyway.
    >
    >
    >Tom

    Alaric Turner wrote:
    > Managers,
    >
    > I seem to have a somewhat strange problem, on a DS20 running 4.0G
    > Patchkit4,
    >
    > every morning around 04:50 /dev/null was changed from a system file to a
    > standard normal file, obviously not correct. By a process of elimination
    > it appears that the daily defragcron job was responsible (since I
    > commented it out in the crontab the problem has not re-occured). however
    > we also run a defragment by directly calling defragment once a week &
    > this seems not to cause a problem.
    >
    > In the short term the problem has been resolved but I would like to
    > re-enable the daily defrag if possible. Has anyone seen a similar problem ?
    >
    > Alaric Turner 

    -- 
Alaric Turner
Systems Manager
Albourne Partners Limited
+44 (0)20 77209201
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