Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uwm.edu!psuvax1!rutgers!att!chinet!les
From: les@chinet.chi.il.us (Leslie Mikesell)
Newsgroups: comp.unix.i386
Subject: Re: backups on 386/ix - some pronblems using GNUtar; any hints?
Keywords: backups, 386ix, GNUtar, tape streamer
Message-ID: <1989Dec5.232732.16194@chinet.chi.il.us>
Date: 5 Dec 89 23:27:32 GMT
References: <481@hades.OZ>
Reply-To: les@chinet.chi.il.us (Leslie Mikesell)
Organization: Chinet - Chicago Public Access UNIX
Lines: 34

In article <481@hades.OZ> greyham@hades.OZ (Greyham Stoney) writes:

>1) When the tape is completely full, GNUtar reports "error opening
>directory ...." for every directory not yet covered. At least, this seems
>to be what's happening. If the tape drive is 120Mb, and the filesystem is
>115Mb, how come the tape fills up at all anyway when doing a full dump???.

Keep in mind that the minimum header block for a tar file is 512 bytes
even for zero length files or linked files that take no actual disk
space.  Try tarring /usr/lib/terminfo to see the problem.  There is
also a possibility that you have sparse files that have their "holes"
filled when you copy them.

>2) When doing a compressed TAR, gnutar's return code incorrectly indicates
>that the tar went OK even if the tape is write protected. Our dump script
>relies on this return code to know whether or not to update the automatic
>tape-contents register we've got.

That probably could be fixed, although I'd rather see per-file compression
so you have some hope of recovery if you have a media error during a
restore.  Anyone working on this (or cpio format output)?

>Has anyone got any hints, or even just general ideas on the best strategy
>I should adopt here?. I don't want to hack GNUtar (much);

You might want to try cpio to see how much space the tar headers are 
actually wasting.  You could still use GNUtar for the incrementals,
since it has a mode where it can delete any files which were not present
when the incremental was taken that is handy if the filesystem is nearly
full or you want to restore that state.


Les Mikesell
  les@chinet.chi.il.us