On Thu, 14 Jun 2001, Russel Ingram wrote:
> On Thu, 14 Jun 2001, Russel Ingram wrote:
>
> > I have added some extra functionality to the pt driver and am looking for
> > people to test it. The attached patch will add the following magnetic
> > tape ops to the driver:
> >
> > MTRETEN -- retention the tape
> > MTLOAD -- load the tape
> > MTUNLOAD -- unload the tape
> > MTERASE -- erase the tape
> > MTWEOF -- write end of file marker
Ah, MTWEOF. I messed with this a while back and kept intending to get
back to this but never did. Filemarks are sufficiently tricky that
when I last messed with them (2.2.8?) the SCSI and IDE tape drivers
did different things. I got confused and never got around to
resolving the confusion. The tricky part is that a write operation
followed by most any other operation really needs a filemark to be
written. I believe the problem was whether a write operation followed
by MTWEOF wrote one or two filemarks. Or something like that.
Anyhow, the difference revolved around whether one or two filemarks
got written (in the QIC-157 sense). And then the behavior of MTFSF
and MTBSF, including which side of the filemark you ended up on, and
whether one filemark was really two QIC-157 marks.
Anyhow, you can tell that 1) the memories are fuzzy, and 2) I'm a bit
confused. We (someone?) should probably figure out/decide what the
"right thing" to do is and try to make all the tape drivers do the
same thing, so that backup software writing a TR-4 tape on a SCSI
drive can read it back transparently on a parallel port drive.
-Scott Berg
-- J. Scott Berg jsberg@earthlink.net 12 ROLLING HILLS DR (631) 924-8613 RIDGE NY 11961-- To unsubscribe, send mail to: linux-parport-request@torque.net -- -- with the single word "unsubscribe" in the body of the message. --
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