Date: Tue, 2 Mar 1999 18:12:43 -0800 (PST) From: Tom <tom@uniserve.com> To: David Kelly <dkelly@hiwaay.net> Cc: freebsd-stable@FreeBSD.ORG Subject: Re: rc5des slows tape thruput Message-ID: <Pine.BSF.4.02A.9903021758210.3610-100000@shell.uniserve.ca> In-Reply-To: <199903030125.TAA10091@nospam.hiwaay.net>
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On Tue, 2 Mar 1999, David Kelly wrote: > Tom writes: > > > The drive at home has 1M of internal RAM, the DDS-3 drives at work have > > > 2M buffers. It would appear FreeBSD doesn't make use of these buffers. > > > > I don't see how that could be. SCSI tapes are SCSI tapes. Any > > buffering done by the device should be invisible. There might be a SCSI > > mode page flag to turn it on or off though. > > What if you write 1MB ahead into the tape drive, then hit the end of > tape? How would one attempt to recover from that? It seems the Un*x > architects intend to be able to recover from that situation altho in > practice its unreliable. It seems only one block at a time is given to > the drive, and the drive doesn't ask for more until the first is safely > on tape. Well, that is assuming the buffer is used for writing. Tom To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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