Only one backup per tape? Really?

[Chip Rosenthal]

In article <NELSON.90Dec12212501 at image.clarkson.edu>
	nelson at clutx.clarkson.edu (aka NELSON at CLUTX.BITNET) writes:
>I've got two filesystems to back up, and only one tape drive, and I'd
>like to do unattended backups.  Can I really only back up one
>filesystem per tape?  Well, of course I mean, will I be able to *restore*
>from a tape with two backups on it?

Use the /dev/nrct0 (no rewind device) instead of /dev/rct0 for the
backups.  It doesn't make doing the backups that much more difficult.

However, doing the restore is a royal pain in the butt.  For example,
if you are using "dump" to make the backups upon /dev/nrct0, what you
need to do for a restore is:

    1) Do enough "tape rfm" commands to get to the dump archive you need.

    2) Run the restore command.  Wait for it to find the files and
       prompt you to insert the backup volume.

    3) Jump over to another multiscreen.

    4) Rewind the tape.

    5) Run the same number of "tape rfm" commands to get back to the
       same archive.

    6) Pop back to the first multiscreen and tell "restore" to continue on.

This is one of the reasons why I use "afio" for XENIX backups.  In Unicom
System Development's Fall '90 newsletter, I did a brief article on afio,
and compared it to dump and cpio for backups.  It included some benchmarks
as well.  If you'd like a copy of the article, send me a snail mail
address.  Afio is available in comp.sources.unix archives (volume 12).

-- 
Chip Rosenthal  512-482-8260  |  We was raising insurance premiums, ma.
Unicom Systems Development    |  We was spreading fear of arson.
<chip at chinacat.Unicom.COM>    |   - Michelle Shocked