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From: emv@math.lsa.umich.edu (Edward Vielmetti)
Newsgroups: comp.unix.questions,comp.unix.ultrix,comp.sys.dec
Subject: multiple dumps on one (exabyte) tape for Dec 3100
Message-ID: <EMV.89Dec20183133@urania.math.lsa.umich.edu>
Date: 20 Dec 89 23:31:33 GMT
Sender: news@math.lsa.umich.edu
Organization: University of Michigan Math Dept., Ann Arbor MI.
Lines: 38


Hi.  I'm trying to arrange it so that I can back up an entire
network of Ultrix systems onto one Exabyte tape overnight,
with no operator intervention.  Slip in a tape at 5 pm, 
take it out at 9 am, no worry, no muss, no fuss.

It would appear that the following problems need to be addressed
before this is going to go, namely:

- dumping live filesystems is a problem.  Fixed with the 
  "Purdue-dump-mods" reposted to alt.sources not too long
  ago.  If a file changes between passes, you don't dump it;
  some files will be missing from the resulting dump tapes
  but the tape will be readable.

- sequencing the dumps so that one doesn't start until the
  previous is finished.  It seems like it would be best to
  have the system with the tape drive control the whole 
  operation.  The 'rrdump' program that just showed up 
  recently would seem to handle that fairly well.

- convincing dump to put more than one dump on a dump tape.
  This I don't have an answer to; any clues?  From all I
  can tell the first thing it does is to rewind the tape.
  I think I've heard of an 'mdump' but I don't have any pointers.

Obviously the best situation would be a mdump program
that could induce other systems start up dump in order,
i.e.

  rmdump 9uf /dev/exabyte elvis:/dev/rz1g orpheus:/dev/rz1g ....

but that's too much to ask.

Free or for-pay solutions welcome, in theory at least I have
access to sources.

--Ed