Path: utzoo!utgpu!watmath!att!dptg!rutgers!usc!ginosko!uunet!virtech!cpcahil
From: cpcahil@virtech.UUCP (Conor P. Cahill)
Newsgroups: comp.unix.xenix
Subject: Re: tar question ...
Message-ID: <1091@virtech.UUCP>
Date: 30 Aug 89 23:15:46 GMT
References: <6340004@hpcupt1.HP.COM>
Organization: Virtual Technologies Inc
Lines: 25

In article <6340004@hpcupt1.HP.COM>, stratton@hpcupt1.HP.COM (Jim Stratton) writes:
> In order to make my backups smaller in 
> size, I compress the tar image using something like this:
>       	tar cf - [files] | compress -c >/tmp/xxx
>       	cd /tmp; tar c xxx; rm xxx
> As an alternative to tar, I've tried piping compress to dd but always get
> an error writing to the output device.
The dd error is probably (and i am really guessing since you didn't display
the command you used) caused by the fact that the output from compress is not
in a nice blocked format that your output device (maybee a tape?) wants.

Under 386/ix I routinely backup 120Meg filesystems to my 60 Meg tape backup
using the following command:

	find . -print | cpio -oBc | compress | dd of=/dev/rmt0 obs=2048k

I know this isn't tar, but substituting tar for the find|cpio should
work without any problem.  The obs=2048k give me a 2Meg output buffer
for the tape, so it streams along when it is writing.  If you do
not have that much memory you might want to reduce it to 50-100 K.
-- 
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| Conor P. Cahill     uunet!virtech!cpcahil      	703-430-9247	!
| Virtual Technologies Inc.,    P. O. Box 876,   Sterling, VA 22170     |
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