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From: harker@well.UUCP (Robert Harker, All around good guy)
Newsgroups: mod.computers.workstations
Subject: Re: Graphics on SUN's;  SUN tape drive operations
Message-ID: <8703180804.AA02788@well.UUCP>
Date: Wed, 18-Mar-87 03:04:41 EST
Article-I.D.: well.8703180804.AA02788
Posted: Wed Mar 18 03:04:41 1987
Date-Received: Fri, 20-Mar-87 01:36:49 EST
References: <14@auscso.UUCP>
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: well!harker@lll-lcc.ARPA (Robert Harker, All around good guy)
Distribution: world
Organization: Whole Earth 'Lectronic Link, Sausalito, CA
Lines: 25
Keywords: Speeding up tape drives
Approved: works@red.rutgers.edu
Summary: /dev/mt device numbers

In article <14@auscso.UUCP> johnl@auscso.UUCP (John Lange) writes:
>My next question is also SUN specific. Does anyone know why the tape
>drives only work at 1600 bpi???  Even the lowly IBM RT can save at
>6250 bpi.  I can't think of a good reason why the SUN workstations
>couldn't save at 6250.  The speed increase would be about a factor
>of 4 with very little additional hardware or software.

Two things could be wrong here:
The first is that your hardware may only support 1600 BPI reads and
writes. If it is a CDC tape drive purchased form Sun, this is the
case.

If your tape drive is a Fujitsu (with a Xylogics tape controller
board) or some other tape drive that supports 6250 BPI, then you may
be using the wrong device number when you write your tape.  If you
tape supports software tape density select then use the following
table to select your drive:
        /dev/rmt0       1600 BPI, rewinding device
        /dev/rmt4       1600 BPI, non-rewinding device
        /dev/rmt8       6250 BPI, rewinding device
        /dev/rmt12      6250 BPI, non-rewinding device

I hope this helps
RLH
harker@well.UUCP (Robert Harker, All around good guy)