Date: Mon, 15 Nov 1999 11:01:05 -0800 (PST) From: Matthew Jacob <mjacob@feral.com> To: "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net> Cc: current@FreeBSD.ORG Subject: Re: FreeBSD 4.0 SCSI Tape Driver Message-ID: <Pine.BSF.4.05.9911151059060.9192-100000@semuta.feral.com> In-Reply-To: <199911151857.KAA15544@gndrsh.dnsmgr.net>
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On Mon, 15 Nov 1999, Rodney W. Grimes wrote: > > > > Reread/reresponse, sorry- ENOCOFFEE: > > > > > > > > > > > > 1 filemark can not be used for EOT, it is EOF, you can't tell if what you > > > > read next is another file or not that may have been left by a previosly > > > > longer usage on the tape. > > > > > > > > > > Well, read until *BLANK CHECK* seems to be what the driver can and should > > do. Let me ponder this some- I believe what I propose actually works fine > > for all the devices we currently support (hell, I use it all the time > > myself). If you can provide an actual example of a SCSI tape device that > > if you take FreeBSD-current or FreeBSD-3.3 and do a 'mt seteotmodel 1' on > > and *not* be able to detect EOT, let me know! > > You won't get ``blank check'' if the tape has previosly been written > past where you just finished writing. Instead you often get trash. Sorry, no. When you write a tape with these devices there's always a leading erased area. That's why if you overwrite the front a tape you can't skip past this area to recover data you really need. A misfeature of modern technology. > > In your other message you talk about the driver getting 2 residuals > in a row, well, unless you write the 2 EOF's you won't always get that... > depends on if the tape drive does it automagically (which many newer > drives do, they write 2 eof's and backspace over 1 of them for you when > ever you tell them to write EOF, the drive itself uses 2 EOF's to > determine logical EOT :-)). I repeat what I said in other mail- can you actually show me a tape drive where what I propose really doesn't work? -matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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