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From: cetron@utah-cs.arpa (Edward J Cetron)
Newsgroups: mod.computers.vax
Subject: Re: disk compresses
Message-ID: <8612021637.AA08990@utah-cs.ARPA>
Date: Tue, 2-Dec-86 11:37:03 EST
Article-I.D.: utah-cs.8612021637.AA08990
Posted: Tue Dec  2 11:37:03 1986
Date-Received: Wed, 3-Dec-86 21:45:47 EST
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Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: utah-cs!cetron (Edward J Cetron)
Organization: Center for Engineering Design, Univ of Utah
Lines: 23
Approved: info-vax@sri-kl.arpa

given that you have 12 ra81's, and disk compress is needed every 14 days, I
see no reason that the whole cluster must go down.....

My suggestions:

	1. Dedicate 1 ra81 for daily temporary files - indicate that every
night at say 4:00 am, this disk will be completely flushed....

	2. Every night at 4:02 am, run a script (woops, wrong OS), an indirect
or batch, command file to do a full backup from one of the 11 other ra81's to
the 12th ra81 (in effect doing a compress) and the reverse the process to 
restore the first ra81 to a compressed state also.  (an option is to access
the ra's by logical name only and rotate the logical names so that you need
do only one backup.....)

	3. have the command file reschedule itself as well as indicating the
next disk of the other 11.... this will give you 1 compressed disk each day
and the full series in 12 days (slightly better than two weeks) and the cluster
can be available (minus 2 disks at some points) all day..

-ed cetron
Center for Engineering Design
Univ. of Utah