Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!seismo!mcnc!gatech!bloom-beacon!think!ames!ucbcad!ucbvax!decvax!tektronix!reed!nscpdc!joer
From: joer@nscpdc.NSC.COM (Joe Rawlings)
Newsgroups: comp.sys.nsc.32k
Subject: Re: ICM3216: appending on tapes.
Message-ID: <885@nscpdc.NSC.COM>
Date: Fri, 17-Jul-87 15:24:36 EDT
Article-I.D.: nscpdc.885
Posted: Fri Jul 17 15:24:36 1987
Date-Received: Sat, 18-Jul-87 18:39:19 EDT
References: <1857@imag.UUCP>
Reply-To: joer@nscpdc.UUCP (Joe Rawlings)
Distribution: world
Organization: NSC Portland Development Center
Lines: 60

Edited for brevity sake:

In article <1857@imag.UUCP> barel@imag.UUCP (Max BAREL) writes:
>I try many times to append on a tape.
>In this way i use the device "/dev/[r]mt/0n" wich must invoque the driver
>with the "no rewind on close" option.
>
>To append on an already written tape one need:
>  -rewind it.
>  -forward skip files already there (with "mt fsf x", or reading them).
>  -then write the new file.
>This don't work (error: can't write output. etc...). I try many sequences
>without success.
>
>If someone could help...
>-- 

There is a difference between the way an end of file (EOF) is marked and
the end of media (EOM) is marked on a cartridge tape.  Skipping the
technical jargon, the EOM is basically two or more EOF markers.  Using the
"mt fsf x" command will take the tape the the EOF marker corresponding to the
end of file structure "x".  When the cpio command is then invoked to write
a new file structure, the tape is checked to determine whether or not
the EOM has been passed (cpio will write at the beginning or end of a tape
only).  Since the "mt" command has NOT placed the tape past all EOF marks,
an error is generated.  This error is NOT FATAL to the operation, in fact,
after the "can't write output. etc", you are given the option to enter
a new device name.  After all this, the EOM has been reached and the cpio 
will succeed.

You do not NEED to rewind the tape if you know where you are on the tape.

Assuming a tape with three file systems.  The tape has been rewound previously
and has just been inserted into the tape drive:

	mt fsf 3
	find . | cpio -oBcv > /dev/rmt/0n
	error message, If you wish to continue enter new device/file name
	/dev/rmt/0
	......

	or

	mt fsf 4
	different error message
	find . | cpio -oBcv > /dev/rmt/0n
	...


Note: This is not a bug, this is the way the commands interact and is
      normal operation.

Cheers,

JR
-- 
/****************************************************************************** *                                                                             *
*  Joe Rawlings                         nsc!nscpdc!joer         or            * *  ICM Product Support                  tektronix!reed!nscpdc!joer            *
*  National Semiconductor Corp.         1-800-222-2433 (outside Oregon)       * *  Portland Development Center          or    629-4414 (inside Oregon)        *
*                                                                             * ******************************************************************************/