From owner-freebsd-scsi Sun Jul 21 23: 0:13 2002 Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id C419D37B401; Sun, 21 Jul 2002 23:00:08 -0700 (PDT) Received: from sax.sax.de (sax.sax.de [193.175.26.33]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1B3F143E4A; Sun, 21 Jul 2002 23:00:06 -0700 (PDT) (envelope-from j@uriah.heep.sax.de) Received: (from uucp@localhost) by sax.sax.de (8.9.3/8.9.3) with UUCP id IAA08400; Mon, 22 Jul 2002 08:00:04 +0200 (CEST) Received: (from j@localhost) by uriah.heep.sax.de (8.11.6/8.11.6) id g6M5pbp68862; Mon, 22 Jul 2002 07:51:37 +0200 (MET DST) (envelope-from j) Date: Mon, 22 Jul 2002 07:51:37 +0200 (MET DST) Message-Id: <200207220551.g6M5pbp68862@uriah.heep.sax.de> Mime-Version: 1.0 X-Newsreader: knews 1.0b.1 Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) Organization: Private BSD site, Dresden X-Phone: +49-351-2012 669 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E References: <20020722033643.GA80263@wantadilla.lemis.com> From: j@uriah.heep.sax.de (Joerg Wunsch) Subject: Re: Seeking beyond EOF on SCSI DDS tapes X-Original-Newsgroups: local.freebsd.scsi To: freebsd-scsi@freebsd.org Cc: "Greg 'groggy' Lehey" Content-Type: text/plain; charset=us-ascii Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org "Greg 'groggy' Lehey" 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