Bug with binary file backup.

Ben Escoto bescoto@stanford.edu
Wed, 06 Feb 2002 15:58:16 -0800

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>>>>> "DS" == Dan Sturtevant <dsturtev@plogic.com>
>>>>> wrote the following on Wed, 6 Feb 2002 18:33:26 -0500 (EST)

  DS> What I was doing was maintaining a tree of the original
  DS> distribution (Plogic-7.1-5) that I was working with and then
  DS> creating deltas by running #rdiff-backup Plogic-7.1-6/ backup/
  DS> followed by #rdiff-backup Plogic-7.1-5 backup/

  DS> I had hoped that this would create a directory structure that
  DS> the end user could place into a copy of the original
  DS> Plogic-7.1-5 tree to get it up to Plogic-7.1-6.

  DS> This creates the opposite problem:  I want older timestamps from
  DS> Plogic-7.1-5 to be pushed on top of Plogic-7.1-6 to generate the
  DS> rdiff-backup-data directory.  It will almost always be the case
  DS> that older files should replace newer ones in my case.

Ok, I can think of 4 things that you could try:

1.  Use my program.  The problem you ran into was that files seemed
    identical because:

  DS> My test directories had the same time because they were coppied
  DS> over to my local machine at the same time.

    So, it seems if you waited a second (e.g. cp ...; sleep 1; cp
    ....)  your immediate problem would go away.

2.  Instead of using CVS use something like PRCS (?) which is better
    at taking binary differences.

3.  I seem to remember someone contributing an extension to rsync
    called rsync+.  I don't know if it has been adopted yet, or how
    stable it is, but the idea is to save the information between
    rsync sessions.  For instance, suppose server 1 always changes,
    and servers 2 and 3 are supposed to be identical copies of 1.  I
    think rsync+ could be run on 1 and 2, and then would produce a
    file that could be transmitted to 3, so 3 could be updated without
    rereading all the files on 1 again.

4.  Make a big tar (uncompressed; just tar) file like Plogic-7.1-5.tar
    or Plogic-7.1-6.tar and then run rdiff on those two files.  You
    can compress the diff and send it around.

I don't know your situation very well, but I would try (4) first, then
(3) if it is stable and easy to use, then (1) and then (2).

  DS> You seem to have a great deal of experience in this domain.
Yep, on the internet no one knows that you're a dog.  :-)

Ben Escoto

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