From: schwager@cs.uiuc.edu (Mike Schwager)
Subject: Re: Backup of 1GB MacHD unix tapedrive
Organization: University of Illinois, Dept. of Comp. Sci., Urbana, IL
Date: Thu, 8 Oct 1992 17:07:55 GMT

olafn@inbit.ibt.unit.no (Olaf F. Normann) writes:

>Hello netters!

>Does anybody know if there exist SW for doing backup of 1GB mac-HD on
>a tape drive (exabyte) connected to a sun sparc?

>I have looked on software called MacDump (which need CAP to run), but
>it stores the backup on the unix disk before it dump's the backup to
>tape,

No it doesn't.  Or, if you're doing it that way, you're doing it wrong.  We
have our Macs dump directly to tape.  We have 20 Mac IIci's with 80 Meg
hd's each.  We do 3 levels of dumps: what we call Daily, Weekly, and
Fulldumps.  Weeklies will save any file that's been touched since the last
fulldump (which are done once/month), and dailies will save any files that
have changed since the last weekly (which are, of course, done once/week).
That way, on any given day, we only need 3 tapes to do a complete restore.

Anyways, we use MacDump (from the University of Utah), even though there is
near *zero* support on it (argh!).  And there is a bug in it- apparently it
will not dump files any larger than 3 Megabytes.  Plus, another strange bug
nipped us: some game was producing a zero-length file.  It made MacDump
hang on that machine.  I'm not sure that was the problem, but it was
something similar to that.  I told the user not to play that game anymore.
Lastly, it can be difficult to set up because if you make a mistake, error
messages are cryptic and often hard to come by.  Besides these problems,
MacDump has worked solidly for us.  And it's cheap.

>and we do not have 1GB free disk space on our sun sparc!
>So, does it exist any SW which copy the backup directly from the Mac to 
>the unix-connected tape drive.

Here is a little part of the script we use (written in perl):

system ("/local/bin/MacDump/getmacback $Machine.cs.uiuc.edu $LastDumpTime | dd conv=block,sync bs=1k\n");

$Machine.cs.uiuc.edu is the name of the Mac.
That command will output the dump in 1K blocks, which is all that our Unix
backup facility (BudTool by Delta Microsystems) needs in order to stuff
things onto tape.  I think you could add an of=/dev/<something> to that
command to make it dump right to tape.

To do a restore, we get the dump file off of Unix tape this way (written in
csh):

dd if=/dev/vrsmt0 of=macback$$ conv=unblock bs=1k

BTW, this will make MacDump complain about a bad archive file, but it seems
to work ok.
The input file is, of course, our tape device.  The problem here is that
since your Mac disk is so big, you won't be able to extract your dump file
on complete backups.  However, the docs specify that one of the client
programs can send a dump archive to a Mac using stdin as the archive.  So
you would have to do a dd pipe, a la:

dd if=<scsi tape> conv=unblock bs=1k | putmacback MacName

I don't know fer sher if that works or not, but I'd lay odds that with the
proper arguments to dd, you could get it to work.  As a matter of fact,
reading the putmacback.c file shows that it reads the archive (in this
case, stdin) in 1k chunks.

Now your only problem remains in doing incremental restores.  You need to
have enough space on disk so that you can place a Mac incremental backup
file on your Sparc.  Or, you need to hack the Unix side a bit to get it to
work.  The source is pretty small; I bet it wouldn't be hard.

If you have any questions, feel free to send me email.
-Mike
aka, Mike Schwager               |"I think we don't have ideology.
INTERNET:schwager@cs.uiuc.edu    | We don't have theology.
                                 | We dance."        -Japanese Shinto Priest
University of Illinois, Dept. of Comp. Sci., for whom I do not speak