Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!noao!asuvax!mcdphx!estinc!fnf
From: fnf@estinc.UUCP (Fred Fish)
Newsgroups: comp.unix.questions
Subject: Re: backup with compressed cpio files ?
Message-ID: <64@estinc.UUCP>
Date: 19 Feb 89 07:09:53 GMT
References: <9100001@netmuc> <872@deimos.cis.ksu.edu> <9667@smoke.BRL.MIL>
Reply-To: fnf@estinc.UUCP (Fred Fish)
Organization: Enhanced Software Technologies, Inc.
Lines: 17

In article <9667@smoke.BRL.MIL> gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>) writes:
>	find . -depth -print | cpio -oc | compress | dd bs=5k > /dev/rmt0

(I'm sure Doug knows this, but for the sake of completeness...)

In order to ensure that dd writes 5K records I believe you have to
specify "ibs" and "obs" to be different sizes, to force an internal
buffer copy.  Substitute "ibs=1k obs=5k" for "bs=5K".  Also note that
the last buffer may not be a full 5k, which may confuse a cpio that
reads the tape directly.

With compress, one read error and you're SOL as far as recovering the rest
of the data.  Of course, vanilla cpio is so braindead that you're SOL
anyway, so you might as well go ahead and compress it...  :-)
-- 
# Fred Fish, 1835 E. Belmont Drive, Tempe, AZ 85284,  USA
# 1-602-491-0048           asuvax!{nud,mcdphx}!estinc!fnf