Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!ncar!mailrus!tut.cis.ohio-state.edu!bloom-beacon!mcgill-vision!mouse
From: mouse@mcgill-vision.UUCP (der Mouse)
Newsgroups: comp.unix.wizards
Subject: Re: Accessing a VAX tape drive from a S
Message-ID: <1281@mcgill-vision.UUCP>
Date: 2 Sep 88 01:03:55 GMT
References: <711@auvax.UUCP> <43200031@uicsrd.csrd.uiuc.edu>
Organization: McGill University, Montreal
Lines: 25

In article <43200031@uicsrd.csrd.uiuc.edu>, kai@uicsrd.csrd.uiuc.edu writes:

> If you are writing data from within a C program, try:

> 	fp = popen ("/usr/ucb/rsh vaxhost /bin/dd of=/dev/rmt8", "w");

You probably don't want to do this.  It's likely to produce unreadable
tapes.  Why?  Because a tape is not just a bytestream; it's got a
record structure to it as well.  When writing a local tape, each
write() call produces one record.  When writing through the network
like this, this is not guaranteed, and in practice will probably not be
so.  Experiment first.  For example, put a tar tape on the drive and do

	tapehost% dd if=/dev/rmt12 of=/tmp/foo
	tapehost% rcp /tmp/foo otherhost:/tmp/foo

then change tapes (put a scratch tape on) and do

	otherhost% rsh tapehost dd of=/dev/rmt12 < /tmp/foo

Then run tar on the resulting tape and notice the complaints.

					der Mouse

			old: mcgill-vision!mouse
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