Original problem (summary):
I need to quickly establish whether you can force a new Exabyte 8500 to
write either 8200 or 8500 format on previously used tapes with Sun's st SCSA
driver on a Sparc2 running SunOS 4.1.1B.
According to the 8500 manual, the mode select parameter determines the
density (format) that the drive will write when positioned at LBOT (Logical
Beginning Of Tape).
0x00 = default mode: EXB8500 mode on an 8500.
0x14 = EXB8200 mode on an 8500.
I modified the Exabyte entry in /sys/scsi/targets/st_conf.c from:
/* Exabyte 8mm cartridge */
{
"Exabyte 8mm Helical Scan", 7, "EXABYTE", ST_TYPE_EXABYTE, 1024,
(ST_VARIABLE | ST_BSF | ST_BSR | ST_LONG_ERASE | ST_AUTODEN_OVERRIDE),
5000, 5000,
{ 0x00, 0x00, 0x00, 0x00 },
{ 0, 0, 0, 0 }
},
to:
/* Exabyte 8mm cartridge */
{
"Exabyte 8mm Helical Scan", 7, "EXABYTE", ST_TYPE_EXABYTE, 1024,
(ST_VARIABLE | ST_BSF | ST_BSR | ST_LONG_ERASE | ST_AUTODEN_OVERRIDE),
5000, 5000,
{ 0x14, 0x00, 0x00, 0x00 },
{ 0, 0, 0, 0 }
},
in an attempt to make st0 emulate an 8200, and to let st8, st16, and st24
operate in native 8500 mode. I rebuilt and installed the new kernel.
However, the result was that it would not force a tape written in 8200 mode
to be rewritten in 8500 mode.
------------------------------------------------------------------------
Solution:
Responses varied from:
a. You can't do this on an 8500. [I think this is not true -- DSN]
b. You can't do this under 4.1.1.
c. You must demagnitize them.
d. Demagnitizing them doesn't work.
e. Use third-party device drivers.
f. Remove the ST_AUTODEN_OVERRIDE from the example above.
g. Install 4.1.2, and the support will be there.
I like the last solution the best. I have not yet installed 4.1.2, but I
extracted the file /sys/scsi/targets/st_conf.c for the sun4c architecture,
and this is what it contains for exabytes:
/* Exabyte 8mm 5GB cartridge */
{
"Exabyte EXB-8500 8mm Helical Scan", 16, "EXABYTE EXB-8500",
ST_TYPE_EXB8500, 1024,
(ST_VARIABLE | ST_BSF | ST_BSR | ST_LONG_ERASE),
5000, 5000,
{ 0x14, 0x00, 0x8C, 0x8C },
{ 0, 0, 0, 0 }
},
/* Exabyte 8mm 2GB cartridge */
{
"Exabyte EXB-8200 8mm Helical Scan", 16, "EXABYTE EXB-8200",
ST_TYPE_EXABYTE, 1024,
(ST_VARIABLE | ST_BSF | ST_BSR | ST_LONG_ERASE | ST_AUTODEN_OVERRIDE),
5000, 5000,
{ 0x00, 0x00, 0x00, 0x00 },
{ 0, 0, 0, 0 }
},
Note that there are now 2 entries for exabytes -- one for 8200s and one for
8500s. The solution I was working on may not have worked for systems with
both 8200s and 8500s, since my entry has 0x14 as the density flag for st0
(which is explict 8200 mode for the 8500, but is an invalid density setting
for a true 8500, which only supports 0x00 for its default density). I don't
have an 8200 and 8500 on the same system, so I can't test it.
I have not tested the 4.1.2 solution, but expect it to work. If it does
not, I will repost revised info. See the note below about the
ST_AUTODEN_OVERRIDE flag.
Additional notes:
------------------------------------------------------------------------
From: keith@lgc.com (Keith W. Brasher)
> SunOS 4.1.2 supports the exabyte 8500. in fact, we've didn't
> realize this when we upgraded to 4.1.2 and our 8500's were writing
> 8200 format tapes because we should have been using rst8 instead of rst0.
> here's a piece of 'man 4 st'
>
> For helical-scan tape devices (Exabyte):
> /dev/rst[0-7]
> Standard EXB-8200 (2GB) Format
> /dev/rst[8-15]
> EXB-8500 (5GB) Format
> /dev/rst[16-23]
> Compressed Format (EXB-8500 only)
> /dev/rst[24-31]
> Compressed Format (EXB-8500 only)
> /dev/nrst[0-7]
> non-rewinding Standard EXB-8200
> (2GB)Format
> /dev/nrst[8-15]
> non-rewinding EXB-8500 (5GB) Format
> /dev/nrst[16-23]
> non-rewinding Compressed Format (EXB-
> 8500 only)
> /dev/nrst[24-31]
> non-rewinding Compressed Format (EXB-
> 8500 only)
>
>
>
If anyone has info on 3rd party support for the 8500 on SunOS 4.1.1, I
would still be interested. Please sent info to keith@lgc.com.
------------------------------------------------------------------------
From: Markus Gutschmidt <gutschmi@informatik.tu-muenchen.dbp.de>
I had to deal these days with the same sort of problem you described in your
posting. I used the modification which Jim Hudgens posted in
comp.sys.sun.hardware . It seems to me that the important thing is to remove
the ST_AUTODEN_OVERRIDE flag. I don't know why, but I did it (SunOs 4.1.1)
in my kernel and it works fine. I can change write format if the tape is at
LBOT (e.g. after rewind) - regardeless of the format the tape had previously.
Hope this helps,
Markus
------------------------------------------------------------------------
Thanks to:
From: jpl@allegra.att.com (John P. Linderman)
From: cyrix!vixen!brian@texsun.Central.Sun.COM (Brian Holgate)
From: George A. Planansky <gplan@aer.com>
From: mark@central.cis.upenn.edu (Mark Foster)
From: keith@lgc.com (Keith W. Brasher)
From: Markus Gutschmidt <gutschmi@informatik.tu-muenchen.dbp.de>
----------------------------------------------------------------
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