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From: kjelle@erialfa.UUCP (Kjell Eriksson)
Newsgroups: comp.unix.wizards
Subject: Dynamic dump level selection.
Message-ID: <161@erialfa.UUCP>
Date: Mon, 19-Oct-87 10:42:21 EDT
Article-I.D.: erialfa.161
Posted: Mon Oct 19 10:42:21 1987
Date-Received: Sat, 24-Oct-87 12:51:31 EDT
Reply-To: kjelle@erialfa.UUCP (Kjell Eriksson)
Organization: Ericsson Information Systems AB, Kista, Stockholm, SWEDEN
Lines: 53
Keywords: backup dump

Hi there, wizards. Here's a problem I have with backups.

Background:

We have a Sun 3/180 running SunOS 3.2 with two Eagles and one 1600 bpi
tapedrive.

We run unattended nightly backups by going to single user mode
sometime in the small hours and running a backup script. This is
started from crontab. The script is run from "/.profile".

We have daily, weekly and monthly backups that runs dump on level 6,
2 and 0 respectivly.

The goal is to keep the incremental backups on as few levels as
possible and one tape per night.

The Problem:

As the activity increases the risk of running out of tape also
increases. 

How do I determine which the lowest dump level is, that fits on one
tape.  I also want to know if I can't fit any dump into only one tape
and if so, switch to a manual backup.

A solution?:

A program that sums blocks and compare their modification dates
against the dates in the /etc/dumpdates.

Before I start hacking. Is there such a beast already? If so where can
I get it? Is there any other solution? (except buying a 6250 drive :-).

I know of one solution to the problem and that is to use dump and
send the output into /dev/null, but there are some problems with this.

a) I have to set the tape size to some very large value to avoid the
   tape switching (yes, on /dev/null :-).

b) It seems waste full to actually read the blocks and dumping them in
   /dev/null.

c) If there is to much data on one level, I have to rerun on the next
   level to see if it fits there.

Help and Thanks in advance

Kjell E.-- 
Kjell Eriksson			Phone: + 46 8 7937844 Telefax: 7509851
Ericsson Information Systems AB	Telex: 15968 ericki s
S-163 98  Stockholm		UUCP:  ...!mcvax!enea!erix!erialfa!kjelle
SWEDEN				       kjelle@erialfa.UUCP