Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uwm.edu!rutgers!bpa!cbmvax!grr
From: grr@cbmvax.commodore.com (George Robbins)
Newsgroups: comp.unix.ultrix
Subject: Re: Multivolume dumps via dump | compress | dd
Keywords: dump dd compress multivolume tk50
Message-ID: <9908@cbmvax.commodore.com>
Date: 1 Mar 90 06:47:05 GMT
References: <25276@ut-emx.UUCP>
Reply-To: grr@cbmvax.cbm.commodore.com (George Robbins)
Organization: Commodore, West Chester, PA
Lines: 34

In article <25276@ut-emx.UUCP> jeff@nic.the.net writes:
> I'm trying to save some space and time by compressing my dumps before writing
> them to tk50 on my DS3100 running UWS 2.1.  I use 
> 
> 	dump 0ucf - /usr | compress | dd of=/dev/rmt0h obs=60k
> 
> to write a dump, which seems to work fine. dd prompts me to replace cartridges
> when appropriate, and dump seems happy. 
> 
> A restore of the form
> 
> 	dd if=/dev/rmt0h ibs=60k | uncompress | restore if -
> 
> works, until the end of the first tape is reached.  I then get "read: i/o
> error" from restore (I think).  dd just tells me its usual records in/out
> count. I've tried using the files=n argument to dd, to no avail.  Can anyone
> shed light on what I'm doing wrong?

Try something like:

(dd if=/dev/rmt0h ibs=60k; mt offline; \
	echo "change tape, hit return" > /dev/tty ; line > /dev/null ; \
	dd if=/dev/rmt0h ibs=60k) | \
    uncompress | restore if -

The trick would be to make the input to uncompress|restore look "seamless"
while actually giving you a chance to change the tape without getting an
error trying to read the tape.

Uh, no, I didn't try it...
-- 
George Robbins - now working for,     uucp:   {uunet|pyramid|rutgers}!cbmvax!grr
but no way officially representing:   domain: grr@cbmvax.commodore.com
Commodore, Engineering Department     phone:  215-431-9349 (only by moonlite)