From owner-freebsd-hackers Sat Jan 6 05:52:12 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id FAA22202 for hackers-outgoing; Sat, 6 Jan 1996 05:52:12 -0800 (PST) Received: from irz301.inf.tu-dresden.de (irz301.inf.tu-dresden.de [141.76.1.11]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id FAA22190 for ; Sat, 6 Jan 1996 05:52:05 -0800 (PST) Received: from sax.sax.de by irz301.inf.tu-dresden.de (8.6.12/8.6.12-s1) with ESMTP id OAA09151 for ; Sat, 6 Jan 1996 14:52:02 +0100 Received: by sax.sax.de (8.6.11/8.6.12-s1) with UUCP id OAA14256 for freebsd-hackers@freebsd.org; Sat, 6 Jan 1996 14:52:01 +0100 Received: (from j@localhost) by uriah.heep.sax.de (8.7.3/8.6.9) id OAA13148 for freebsd-hackers@freebsd.org; Sat, 6 Jan 1996 14:05:30 +0100 (MET) From: J Wunsch Message-Id: <199601061305.OAA13148@uriah.heep.sax.de> Subject: Re: A few NITS about SCSI Tapes To: freebsd-hackers@freebsd.org (FreeBSD hackers) Date: Sat, 6 Jan 1996 14:05:29 +0100 (MET) Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) In-Reply-To: <199601050103.UAA21083@spooky.rwwa.com> from "Robert Withrow" at Jan 4, 96 08:03:23 pm X-Phone: +49-351-2012 669 X-Mailer: ELM [version 2.4 PL23] MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: owner-hackers@freebsd.org Precedence: bulk As Robert Withrow wrote: > > I don't see any way to retension a qic-150 tape with mt. ``mt eom'' > doesn't go to the end, and cating the device to /dev/null is > problematic when the tape actually *needs* to be retensioned (as > in you get errors reading...). I just had to learn that the SCSI-2 standard actually defines a way to retension a tape. (It's done by the Re-Ten bit of a load operation in the LOAD UNLOAD command.) ``A re-tension (Re-Ten) bit of one indicates that the medium on the logical unit shall be correctly tensioned. Implementation of the re-tension function is device specific.'' Well, this would give us a way to implement it. What is the suggested timeout for such a command? (I.e., how long do some SCSI tapes need in order to retension a cartridge?) Is 1800 seconds enough? If somebody wants to try it, here's the magic: scsi -s 1800 -f /dev/st0ctl.0 -c "1b 0 0 0 0:b5 v:b1 v:b1 v:b1 0" 0 1 1 ^^^^ ^ ^ ^ timeout EOT _________/ | | Re-Ten ___________/ | Load _____________/ See the SCSI-2 docs for an explanation of the EOT bit. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)