Date: Mon, 22 Jul 2002 07:51:37 +0200 (MET DST) From: j@uriah.heep.sax.de (Joerg Wunsch) To: freebsd-scsi@freebsd.org Cc: "Greg 'groggy' Lehey" <grog@freebsd.org> Subject: Re: Seeking beyond EOF on SCSI DDS tapes Message-ID: <200207220551.g6M5pbp68862@uriah.heep.sax.de> References: <20020722033643.GA80263@wantadilla.lemis.com>
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"Greg 'groggy' Lehey" <grog@FreeBSD.ORG> wrote: > All positioning commands that I know stop after a double tape mark. > Is there any diagnostic command which can get beyond the double tape > mark? Actually, it's not the double tape mark (you can write as many tape marks as you want, and go past them), but all the modern drives keep track of what the SCSI standard describes as `end of recorded medium' (EOM) internally, and don't let you go past that with any command. The standard trick for QIC tapes was to start recording something from the beginning, and once you're certain you are beyond the current EOM point, to power-off the device while still writing. This gives the device no chance to write a new EOM label onto the tape. I have no idea whether this would work for a DDS drive as well, but it might be worth a try. Only old reel-to-reel drives don't have a notion of EOM, thus it has been emulated by the driver by writing two successive tape marks. -- cheers, J"org .-.-. --... ...-- -.. . DL8DTL http://www.sax.de/~joerg/ NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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