From owner-freebsd-scsi Fri Mar 19 6:29:15 1999 Delivered-To: freebsd-scsi@freebsd.org Received: from ren.detir.qld.gov.au (ns.detir.qld.gov.au [203.46.81.66]) by hub.freebsd.org (Postfix) with ESMTP id ED65514CEB for ; Fri, 19 Mar 1999 06:29:11 -0800 (PST) (envelope-from syssgm@detir.qld.gov.au) Received: by ren.detir.qld.gov.au; id AAA24508; Sat, 20 Mar 1999 00:28:39 +1000 (EST) Received: from ogre.detir.qld.gov.au(167.123.8.3) by ren.detir.qld.gov.au via smap (3.2) id xma024500; Sat, 20 Mar 99 00:28:23 +1000 Received: from atlas.detir.qld.gov.au (atlas.detir.qld.gov.au [167.123.8.9]) by ogre.detir.qld.gov.au (8.8.8/8.8.7) with ESMTP id AAA15531; Sat, 20 Mar 1999 00:28:22 +1000 (EST) Received: from nymph.detir.qld.gov.au (nymph.detir.qld.gov.au [167.123.10.10]) by atlas.detir.qld.gov.au (8.8.5/8.8.5) with ESMTP id AAA10101; Sat, 20 Mar 1999 00:28:22 +1000 (EST) Received: from nymph.detir.qld.gov.au (localhost.detir.qld.gov.au [127.0.0.1]) by nymph.detir.qld.gov.au (8.8.8/8.8.7) with ESMTP id AAA12777; Sat, 20 Mar 1999 00:28:20 +1000 (EST) (envelope-from syssgm@nymph.detir.qld.gov.au) Message-Id: <199903191428.AAA12777@nymph.detir.qld.gov.au> To: mjacob@feral.com Cc: freebsd-scsi@FreeBSD.ORG, syssgm@detir.qld.gov.au Subject: Re: Strange SCSI QIC tape behaviour References: In-Reply-To: from Matthew Jacob at "Sat, 13 Mar 1999 09:17:04 -0800" Date: Sat, 20 Mar 1999 00:28:19 +1000 From: Stephen McKay Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org I've discovered a little more about the behaviour of the TDC4200 as it relates to the current driver and fixed vs variable blocking. My earlier message described some of my difficulty reusing variable blocked tapes, even after 'mt erase'. I have just found that 'mt density 0' is required or you get nowhere. Strangely, it seems to have no effect as far as 'mt status' is concerned, though it certainly changed the behaviour of the drive. I think the SCSI tape driver maintains some sort of state that is out of date, and maintains it even over reinsertions of the tape media. So 'mt density 0' just gets it to resync with what the drive thinks is going on. I got as far as sasetparams() in scsi_sa.c, but now I know I need to read a lot more of the SCSI spec, and that could take quite some time. Stephen. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message