[4681] in linux-scsi channel archive
Hardware compression on WangDat 3800
daemon@ATHENA.MIT.EDU (Michael Meissner)
Wed Sep 9 21:44:37 1998
Date: Wed, 9 Sep 1998 18:18:57 -0400
From: Michael Meissner <meissner@cygnus.com>
To: linux-scsi@vger.rutgers.edu
I just got a WangDat 3800 DAT DDS-2 tape drive (using 2.1.105 of the
kernel, an Adaptec 2940UW controller with Doug's latest patches,
though for any driver specific features, I may decide to move it to a
TekRam 390F with a Symbios 53c875 chipset, and 3.0g of the driver
installed). I can't seem to get hardware compression enabled. I've
tried setting the jumper in the back both ways. I've tried using 'mt
compression 1', and even 'mt compression 0'. Is there some secret of
how to get the tape to do hardware compression?
In terms of blocksizes, etc. I use the 0.5 version of 'mt' to set
compression 0 or 1, and set the block size to 8192 as well (I just
started a dump using 512). Unlike my Archive DDS-1, the operation
light isn't constant, it blinks on of off, which I would imagine means
I'm not streaming the drive. I do not notice the left hand light
comming on, which means the tape hasn't reported an error yet. I use
roughly the command:
find <disk> -xdev -print | cpio -o -H crc --sparse -C 8192 \
| dd of=/dev/nst0 bs=8192
to dump to the tape, and dump several disk volumes. The machine is a
dual processor Pentium Pro with 128 megabytes of memory.
As a side note, using 2.1.105, the verify step hangs if I use a block
size larger than 8192.
--
Michael Meissner, Cygnus Solutions (Massachusetts office)
4th floor, 955 Massachusetts Avenue, Cambridge, MA 02139, USA
meissner@cygnus.com, 617-354-5416 (office), 617-354-7161 (fax)
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