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From: joer@nscpdc.NSC.COM (J.H.Rawlings III)
Newsgroups: comp.sys.nsc.32k
Subject: Re: ICM3216: appending on tapes.
Message-ID: <887@nscpdc.NSC.COM>
Date: Wed, 22-Jul-87 13:25:25 EDT
Article-I.D.: nscpdc.887
Posted: Wed Jul 22 13:25:25 1987
Date-Received: Sat, 25-Jul-87 01:57:47 EDT
References: <1857@imag.UUCP> <885@nscpdc.NSC.COM> <258@devel.cats.oz>
Reply-To: joer@nscpdc.UUCP (J.H.Rawlings III)
Distribution: world
Organization: NSC Portland Development Center
Lines: 46


In article <258@devel.cats.oz> gfm@devel.cats.oz (Graham Menhennitt) writes:

>If your tape device driver is written correctly you won't have this problem.
>The correct way of handling a close on a tape device that has been open for
>writing is to mark it with an EOM. As Joe says this is simply two EOF marks.
>The trick is that after writing the second mark the device driver should
>backspace the tape to the point between the two marks. Then, if the non-rewind
>tape device was used and the device is subsequently re-opened for writing,
>the second EOF will be overwritten and the tape will correctly have one EOF
>between the two files.

This is the way that the tape device driver works.  Note that multiple
"cpio" files can be written to tape as long as they are written in one
session with the non-rewind driver.  Once the tape has been rewound, the
"error message senario" is mandated.


In article  <219@augean.OZ> idall@augean.OZ (Ian Dall) writes:

>The trouble is that the erase head is the full width of the tape and erasing
>is automatically done on a write to track 1.
					   ^ 
Should be track 0.
					   
>What is really needed is a modification to the "mt" command to support
>"mt eod".

Yes, and recognizing that, we at National Semiconductor Corporation Portland
Development Center (NSCPDC) have done just that.  In the newest release of
the System V/Series 32000 (tm) Software (revision F), the "mt" command has been
modified so that "cpio" commands can be appended to tape even if the tape
has been rewound.  The new command is "mt -f  append" where 
refers to the tape device (usually /dev/rmt/0n).

How new is this release?  It was released yesterday, (Tues, 7/21/87).

NSCPDC periodically produces maintenance releases to fix reported bugs and
to add enhancements, (requested and otherwise).  For more information about
the newest release, call the NSCPDC Technical Support Hot-Line.

-- 
/****************************************************************************** *                                                                             *
*  Joe Rawlings                         nsc!nscpdc!joer                       * *  ICM Product Support                  tektronix!reed!nscpdc!joer            *
*  National Semiconductor Corp.         1-800-222-2433 (outside Oregon)       * *  Portland Development Center          (503)-629-4414 (Oregon/World)         *
*                                                                             * ******************************************************************************/