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From: Julian Elischer <julian@ref.tfs.com>
Message-Id: <199602190651.WAA08100@ref.tfs.com>
Subject: Re: Exabyte 8mm tape drive performance in -current?
To: bob@luke.pmr.com (Bob Willcox)
Date: Sun, 18 Feb 1996 22:51:39 -0800 (PST)
Cc: gibbs@freefall.freebsd.org, freebsd-current@freefall.freebsd.org
In-Reply-To: <199602190259.UAA02614@luke.pmr.com> from "Bob Willcox" at Feb 18, 96 08:59:11 pm
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> 
> Justin T. Gibbs wrote:
> > 
> 
> bob@han-p1 /home/bob> mt -f /dev/rst2 status     
> Present Mode:   Density = 0x00         Blocksize = 512 bytes
> ---------available modes---------
> Mode 0:         Density = 0x00         Blocksize = 512 bytes
> Mode 1:         Density = X3.136-1986  Blocksize = 512 bytes
> Mode 2:         Density = X3.39-1986   Blocksize variable
> Mode 3:         Density = X3.54-1986   Blocksize variable
> 
> is what mt status looks like.  Note that I am unable to change the
> blocksize to 0 (or anything else) with the mt blocksize command.

This looks like it's interpretting it to be an unknown tape type..
this is correct. Though I disagree a little with the default settings
        {   
                T_SEQUENTIAL, T_SEQUENTIAL, T_REMOV, "*", "*", "*",
                "st", SC_ONE_LU, 0, mode_unktape
        },
AND
static st_modes mode_unktape =
        {
            {512, ST_Q_FORCE_FIXED_MODE, 0},            /* minor 0,1,2,3 */
            {512, ST_Q_FORCE_FIXED_MODE, QIC_24},       /* minor 4,5,6,7 */ 
            {0, ST_Q_FORCE_VAR_MODE, HALFINCH_1600},    /* minor 8,9,10,11 */
            {0, ST_Q_FORCE_VAR_MODE, HALFINCH_6250}     /* minor 12,13,14,15 *

I thinkthe first line should be:
{0,0,0}
which would allow it to try askthe drive what it wants,
similar to what it did before....


read st(4) to understand about 'mount sessions'
I know that justin changed this a little but I believe it's still valid.

try the following:
mt -f /dev/sd0ctl.0 blocksize 0

your previou scommands were probably only lasting as long as the 'open'
(which was as long as the 'mt' command.)
did you do the blocksize command to rst0 or nrst0?

julian