From owner-freebsd-arch Tue Dec 21 0:34: 1 1999 Delivered-To: freebsd-arch@freebsd.org Received: from ns1.yes.no (ns1.yes.no [195.204.136.10]) by hub.freebsd.org (Postfix) with ESMTP id 6362014F31 for ; Tue, 21 Dec 1999 00:33:58 -0800 (PST) (envelope-from eivind@bitbox.follo.net) Received: from bitbox.follo.net (bitbox.follo.net [195.204.143.218]) by ns1.yes.no (8.9.3/8.9.3) with ESMTP id JAA07963 for ; Tue, 21 Dec 1999 09:33:56 +0100 (CET) Received: (from eivind@localhost) by bitbox.follo.net (8.8.8/8.8.6) id JAA24632 for freebsd-arch@freebsd.org; Tue, 21 Dec 1999 09:33:56 +0100 (MET) Received: from feral.com (feral.com [192.67.166.1]) by hub.freebsd.org (Postfix) with ESMTP id 218B914F31 for ; Tue, 21 Dec 1999 00:33:50 -0800 (PST) (envelope-from mjacob@feral.com) Received: from beppo.feral.com (beppo [192.67.166.79]) by feral.com (8.9.3/8.9.3) with ESMTP id AAA14972; Tue, 21 Dec 1999 00:35:31 -0800 Date: Tue, 21 Dec 1999 00:35:31 -0800 (PST) From: Matthew Jacob Reply-To: mjacob@feral.com To: Bob Bishop Cc: "Rodney W. Grimes" , freebsd-arch@freebsd.org, Stephen McKay , Greg Lehey , Thomas David Rivers , Joerg Wunsch , Hauke Fath Subject: Re: filemarks? In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > >> Whats wrong with this model? > > > >The user application cannot distinguish EARLY WARNING from hard EOT directly. > >You can put more data on tape after EARLY WARNING and before hard EOT. > > I'm not sure you can, in general [because not all drives will give you > sufficient warning]. The best you can guarantee is that closing the device > at this point will leave the tape in a state where a subsequent reader > won't get confused. EARLY WARNING is actually configurable for most SCSI drives. If you don't get EARLY WARNING (which is the EOM bit in sense data) associated with a plain old UNIT ATTENCTION sense key, you'll get a VOLUME OVERFLOW sense key (hard EOT). As far as I know you usually don't get EARLY WARNING detection on reads for these drives- this only happens on writes- I don't have my specs handy or I'd go back and make sure of this. The way I was specifying this is that subsequent reads aren't confused by this at all. If you miss EARLY WARNING (say the drive isn't strapped for it), you get VOLUME OVERFLOW (hard EOT) anyway on writes. -matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message