Summary: Backups to a 8mm drive using /etc/dump

From: Michael R. Zika (
Date: Mon Apr 12 1993 - 15:33:30 CDT

The original question was:
> I'm trying to get a more sensible dump schedule down using
> /etc/dump in SunOS 4.1.3. I would like to be able to dump all
> partitions to the same 8mm tape as follows (for example):
> /dev/sd0a (/) level 0 starts as file 1
> /dev/sd0g (/usr) level 0 starts as file 2
> However, I can't seem to get the series of commands correct. I
> expected the following to work:
> % dump 0ubdsf 126 54000 13000 /dev/rst8 /dev/sd0a
> % restore tf /dev/rst8 > root.toc
> % mt -f /dev/rst8 fsf 1
> % dump 0ubdsf 126 54000 13000 /dev/rst8 /dev/sd0g
> % restore tf /dev/rst8 > usr.toc
> The tables of contents are correct. However, I can't seem to
> be able to go back to the beginning of the tape and recover the
> root table of contents. This leads me to believe that the dump
> of /usr has overwritten the dump of /.

  The obvious answer was: Use /dev/nrst8 everywhere for /dev/rst8.
The "n" prefix stands for No-Rewind. So, the command:

% mt -f /dev/rst8 fsf 1

positions the tape after the next EOF marker and then promptly
rewinds the tape (and you can just hear that CPU saying "I know
better what you want to do that you do!")

  To cut down on the rewinds and fast forwards, I changed the
script to execute something like:

% mt -f /dev/nrst8 rewi
% dump 0ubdsf 126 54000 13000 /dev/nrst8 /dev/sd0a
% dump 0ubdsf 126 54000 13000 /dev/nrst8 /dev/sd0g
% mt -f /dev/nrst8 rewi
% restore tf /dev/nrst8 > root.toc
% mt -f /dev/nrst8 fsf 1
% restore tf /dev/nrst8 > usr.toc

  One (good) question was why I wasn't using the "archive" option
in dump:

% dump 0ubdsfa 126 54000 13000 root.archive /dev/nrst8 /dev/sd0a

When I experimented with this option, it seemed (note: _very_ limited
testing) that the archive file was larger than the toc, so, in the
interest of disk space, I chose to use the restore command to
obtain the toc. Ed Kos pointed out that creating an archive would
save wear and tear on the drive and allow and interactive browsing
of the tape without having to load it or restore anything:

% restore -ivf root.archive

These are _excellent_ points -- I will probably be changing my
script accordingly.

  Many thanx to all who replied (and are replying -- my inbox runneth
over). I've lost the majority of those who replied, sorry -- you
know who you are! Thanx again.

--Michael Zika

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