Newsgroups: comp.unix.ultrix
Path: utzoo!utgpu!watserv1!watcgl!idallen
From: "Ian! D. Allen [CGL]" <idallen@watcgl.waterloo.edu>
Subject: Be careful using dd to write multiple volumes
Message-ID: <1990Oct10.051524.12610@watcgl.waterloo.edu>
Sender: idallen@watcgl.waterloo.edu (Ian! D. Allen [CGL])
Organization: Computer Graphics Laboratory, University of Waterloo, Ontario, Canada
Date: Wed, 10 Oct 90 05:15:24 GMT
Lines: 19

Ultrix 3.1C DS5400

I wrote some TK70 dump tapes like this:

    dump 0f - /whatever | compress | dd ibs=8k obs=32k of=/dev/rmt0h

Where the dd took two tapes, I cannot read it back:

    dd bs=32k if=/dev/rmt0h | uncompress | restore if -

dd eventually asks for the next volume, then uncompress dies with some
error about "not in compressed format" or some such when the second
tape is started.  I havent got 600Mb of space to try extracting the
two tapes into at the moment, to see if uncompress will read one 600Mb
file off disk.  I imagine dd might be mis-handling the block that
spans the two tapes.
-- 
-IAN! (Ian! D. Allen) idallen@watcgl.uwaterloo.ca idallen@watcgl.waterloo.edu
 [129.97.128.64]  Computer Graphics Lab/University of Waterloo/Ontario/Canada