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From: J Wunsch <j@uriah.heep.sax.de>
Message-Id: <199601132233.XAA02099@uriah.heep.sax.de>
Subject: Re: A few NITS about SCSI Tapes
To: freebsd-hackers@freebsd.org (FreeBSD hackers)
Date: Sat, 13 Jan 1996 23:33:52 +0100 (MET)
Cc: wilko@yedi.iaf.nl (Wilko Bulte)
Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch)
In-Reply-To: <199601131805.TAA00481@yedi.iaf.nl> from "Wilko Bulte" at Jan 13, 96 07:05:12 pm
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As Wilko Bulte wrote:
> 
> Sidestepping a bit: will 2.1R mt also set (no)compression on Exabytes
> capable of hardware compress? The &*^*( drive at work is a 8505 and
> my ol' home 8200 does not grok compressed tapes.

Nobody bothered to implement it so far.

Please, try to patch your /usr/share/misc/scsi_modes with:

Index: share_misc/scsi_modes
===================================================================
RCS file: /home/cvs/src/share/misc/scsi_modes,v
retrieving revision 1.3
diff -u -r1.3 scsi_modes
--- scsi_modes	1995/12/28 14:24:08	1.3
+++ scsi_modes	1996/01/13 22:02:18
@@ -229,3 +229,32 @@
 	{Output Port 3 Channel Selection} t4
 	{Output Port 3 Volume} i1
 }
+
+# Sequential-access Device Configuration Page
+
+0x10	{
+	{Reserved} *t1
+	{CAP} t1
+	{CAF} t1
+	{Active Format} t5
+	{Active Partition} i1
+	{Write Buffer Full Ratio} i1
+	{Read Buffer Empty Ratio} i1
+	{Write Delay Time} i2
+	{DBR} t1
+	{BIS} t1
+	{RSmk} t1
+	{AVC} t1
+	{SOCF} t2
+	{RBO} t1
+	{REW} t1
+	{Gap Size} i1
+	{EOD Defined} t3
+	{EEG} t1
+	{SEW} t1
+	{Reserved} *t3
+	{Buffer Size at Early Warning} i3
+	{Select Data Compression Algorithm} i1
+	{Reserved} *i1
+}
+

...and see if you could edit the ``Select Data Compression Algorithm''
field to ``1'' using:

	scsi -f /dev/st0ctl.0 -m 0x10 -e

(Don't worry about the dozens of acronyms.  They are taken straight
out of the SCSI-2 document, but you won't care too much anways.)

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)