From owner-freebsd-scsi Thu Apr 9 09:27:57 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id JAA04179 for freebsd-scsi-outgoing; Thu, 9 Apr 1998 09:27:57 -0700 (PDT) (envelope-from owner-freebsd-scsi@FreeBSD.ORG) Received: from panzer.plutotech.com (ken@panzer.plutotech.com [206.168.67.125]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id JAA04166 for ; Thu, 9 Apr 1998 09:27:54 -0700 (PDT) (envelope-from ken@panzer.plutotech.com) Received: (from ken@localhost) by panzer.plutotech.com (8.8.8/8.8.5) id KAA07550; Thu, 9 Apr 1998 10:26:53 -0600 (MDT) From: "Kenneth D. Merry" Message-Id: <199804091626.KAA07550@panzer.plutotech.com> Subject: Re: compression on Exabyte 8700LT? In-Reply-To: <199804091527.QAA09483@albatross.mcc.ac.uk> from Ian Pallfreeman at "Apr 9, 98 04:27:31 pm" To: ip@mcc.ac.uk Date: Thu, 9 Apr 1998 10:26:53 -0600 (MDT) Cc: scsi@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL28s (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Ian Pallfreeman wrote... > I've recently acquired another Exabyte drive, an 8700LT. This drive claims to > be able to write 10Gb to a 112m tape in compressed mode, but I'm getting just > the 5Gb I'd expect uncompressed. > > There are no switches other than the SCSI id on the box. The manual tells me > to enable compression in software. ``mt -f /dev/rst1 comp 1'' logs the error > "select returned an error of 5" to the console and gives me an I/O error from > mt(1). > > How do I permanently enable compression? > > FreeBSD 3.0-CURRENT #9: Thu Apr 9 16:06:09 BST 1998 > ip@lurch:/usr/src/sys/compile/LURCH > [...] > ahc0: rev 0x00 int a irq 9 on pci0.19.0 > ahc0: aic7880 Single Channel, SCSI Id=7, 16/255 SCBs > [...] > st0 at scbus0 target 4 lun 0 > st0: type 1 removable SCSI 2 > st0: Sequential-Access density code 0x13, drive empty > st1 at scbus0 target 5 lun 0 > st1: type 1 removable SCSI 2 > st1: Sequential-Access density code 0x0, drive empty Well, this may be fixed by PR kern/5274. Basically, the page format bit isn't being set when a mode select is done on the drive, so the drive probably thinks it's a SCSI-1 mode select, and doesn't pay attention to the compression page. So, you might want to try applying the patch in that PR, and see if it fixes your problem. Most drives I've seen come with compression turned on by default, but maybe yours doesn't. The next CAM snapshot fixes this. (at least on the 6 tape drives I've tested it on) mt(1) will tell you whether compression is supported or turned on for your drive. (and which type of compression is in use) For instance: sa0 at ahc0 bus 0 target 5 lun 0 sa0: Removable Sequential Access SCSI2 device sa0: 5.0MB/s transfers (5.0MHz, offset 15) {bladerunner:/usr/home/ken:4:0} mt status Mode Density Blocksize bpi Compression Current: X3B5/88-185A 512 bytes 61000 unsupported ---------available modes--------- 0: X3B5/88-185A 512 bytes 61000 unsupported 1: X3B5/88-185A 512 bytes 61000 unsupported 2: X3B5/88-185A 512 bytes 61000 unsupported 3: X3B5/88-185A 512 bytes 61000 unsupported sa1 at ahc1 bus 0 target 4 lun 0 sa1: Removable Sequential Access SCSI2 device sa1: Serial Number 00263194 sa1: 4.32MB/s transfers (4.32MHz, offset 11) {bladerunner:/usr/home/ken:7:0} mt -f /dev/nrsa1 status Mode Density Blocksize bpi Compression Current: 0x00 1024 bytes 0 unsupported ---------available modes--------- 0: 0x00 1024 bytes 0 unsupported 1: 0x00 1024 bytes 0 unsupported 2: 0x00 1024 bytes 0 unsupported 3: 0x00 1024 bytes 0 unsupported sa2 at adv1 bus 0 target 2 lun 0 sa2: Removable Sequential Access SCSI2 device sa2: Serial Number 16012000 sa2: 5.0MB/s transfers (5.0MHz, offset 15) {bladerunner:/usr/home/ken:9:0} mt -f /dev/nrsa2 status Mode Density Blocksize bpi Compression Current: 0x00 1024 bytes 0 IDRC ---------available modes--------- 0: 0x00 1024 bytes 0 IDRC 1: 0x00 1024 bytes 0 IDRC 2: 0x00 1024 bytes 0 IDRC 3: 0x00 1024 bytes 0 IDRC sa0 at ahc0 bus 0 target 5 lun 0 sa0: Removable Sequential Access SCSI2 device sa0: 5.0MB/s transfers (5.0MHz, offset 8) {thunderdome:/usr/home/ken:5:0} mt status Mode Density Blocksize bpi Compression Current: X3B5/88-185A 512 bytes 61000 DCLZ ---------available modes--------- 0: X3B5/88-185A 512 bytes 61000 DCLZ 1: X3B5/88-185A 512 bytes 61000 DCLZ 2: X3B5/88-185A 512 bytes 61000 DCLZ 3: X3B5/88-185A 512 bytes 61000 DCLZ For some reason, Exabyte drives don't like to report any density information. Go figure. Ken -- Kenneth Merry ken@plutotech.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message