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From: mkhaw@teknowledge-vaxc.UUCP
Newsgroups: comp.unix.questions,comp.unix.wizards
Subject: "tar  | dd " question
Message-ID: <13658@teknowledge-vaxc.ARPA>
Date: Sat, 13-Jun-87 17:23:31 EDT
Article-I.D.: teknowle.13658
Posted: Sat Jun 13 17:23:31 1987
Date-Received: Sun, 14-Jun-87 05:39:44 EDT
Organization: Teknowledge, Inc., Palo Alto CA
Lines: 25
Xref: utgpu comp.unix.questions:2469 comp.unix.wizards:2477

I often use a pipe like

	tar cBf - . | rsh remote dd of=/dev/rmt12 bs=20b

to make 9-track tapes from Unix hosts w/o local 9-track drives.  If I then
try to read the tape on a host with a local 9-track drive using just tar alone,
I get a directory checksum error or a diagnostic about blocksize (I forget
which it is).

Should I omit "bs=20b", use another value for blocking, or is there an
additional parameter I can give to 'dd' in the above pipe -- like "conv=unblock"
-- so that I won't have to use a "dd | tar x" pipe to read back from the tape?

By the way, when tar'ing (1) to 6250bpi 9-track, (2) over ethernet, are
there larger blocksizes I can use?  The Ultrix man file for tar claims
the default 20 blocks (of 512 bytes) is the maximum for 9 track tape, but
I've used 126b with no problem, like a lot of Sun s/w vendors do for 1/4 in.
tar cartridges.

Thanks,
Mike Khaw
-- 
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