From owner-freebsd-scsi Wed Apr 28 23:24:39 1999 Delivered-To: freebsd-scsi@freebsd.org Received: from sax.sax.de (sax.sax.de [193.175.26.33]) by hub.freebsd.org (Postfix) with ESMTP id 1EF3B14E00 for ; Wed, 28 Apr 1999 23:24:33 -0700 (PDT) (envelope-from j@uriah.heep.sax.de) Received: (from uucp@localhost) by sax.sax.de (8.8.8/8.8.8) with UUCP id IAA15510 for freebsd-scsi@FreeBSD.ORG; Thu, 29 Apr 1999 08:24:32 +0200 (CEST) (envelope-from j@uriah.heep.sax.de) Received: (from j@localhost) by uriah.heep.sax.de (8.9.3/8.9.1) id IAA03062; Thu, 29 Apr 1999 08:20:07 +0200 (MET DST) (envelope-from j) Message-ID: <19990429082006.15161@uriah.heep.sax.de> Date: Thu, 29 Apr 1999 08:20:06 +0200 From: J Wunsch To: freebsd-scsi@FreeBSD.ORG Subject: Re: QIC tape problems on -stable (was: hanging `tar xfvR /dev/nrst0' process, can i debug it?) Reply-To: Joerg Wunsch References: <19990428210836.47084@uriah.heep.sax.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.88 In-Reply-To: ; from Matthew Jacob on Wed, Apr 28, 1999 at 01:43:58PM -0700 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 Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org As Matthew Jacob wrote: > > So what's the > > scenario where you think you really need another WRITE FILEMARKS with > > a count of 0? > > At < 10MB/s tape transport speed you'll have data in the tape buffers for > geologic time after you've finished the WRITE command (remember- you're in > buffered mode) and want to read position. Well, but you didn't read the remainder of my article, did you? The thing is, before you can get at issuing an ioctl(MTIOCRD*POS), unless you're doing this inside the application that's currently writing (none of the existing apps would do so), the application writing data has to close the tape device first. Closing the tape device after a write operation always results in writing at least one filemark (withouth the `Imm' bit set in the CCB), so this by definition flushes the write buffer. -- 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. ;-) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message