Date: Tue, 29 Aug 2000 13:17:21 +0930 From: Greg Lehey <grog@lemis.com> To: Matthew Jacob <mjacob@feral.com> Cc: Sam <freep@thecity.sfsu.edu>, freebsd-scsi@FreeBSD.ORG Subject: Re: "tape is now frozen" Message-ID: <20000829131721.R11422@wantadilla.lemis.com> In-Reply-To: <Pine.BSF.4.21.0008282031330.36166-100000@beppo.feral.com>; from mjacob@feral.com on Mon, Aug 28, 2000 at 08:36:42PM -0700 References: <20000829130040.Q11422@wantadilla.lemis.com> <Pine.BSF.4.21.0008282031330.36166-100000@beppo.feral.com>
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On Monday, 28 August 2000 at 20:36:42 -0700, Matt Jacob wrote: > On Tue, 29 Aug 2000, Greg Lehey wrote: >> On Tuesday, 8 August 2000 at 16:39:03 -0700, Matt Jacob wrote: >>>> >>>> Indeed, it looks like he omitted the message that we most wanted to >>>> see. >>>> >>>> Let me repeat here that I find this *very* irritating. It happens, >>>> for example, if I try to read a block which is too long. There's no >>>> way to know the length of a tape block in advance, so this is >>>> relatively easy to get, particularly with DDS-4 drives, and it >>> >>> This error should not occur if you're in variable block mode. If you >>> set the drive in fixed block mode and read a block that's too large, >>> the tape driver cannot know where the tape heads are located. It's >>> that simple. >> >> It's not that simple. If it happens in the middle of the tape, I need >> to rewind the bloody thing to recover. At least an fsf or bsf should >> be sufficient. > > So you space a filemark. Where specfically on the tape are you given you've > lost knowledge of where you are? I've lost the *exact* position. In fact, I'm not even sure I've lost the exact position, but I'm prepared to concede that. Within a block or so I know where I am. > The whole point of rewind, eom or offline is to bring the tape to a > *known* place. Spacing one filemark is not sufficient. Why not? We know we're at the beginning (or end) of a file. > I thought for awhile about allowing the use of rdhpos/sethpos to allow > for unfreezing. > > You're also, again, begging the question as to why it has occurred. Well, no, I state it above. > It has occurred because there was an I/O error, or you're not using > the tape correctly (fixed block mode and you don't issue the correct > read size). Precisely. But that's not a reason to penalize people by making them wind from one end of the tape to the other. Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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