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List:       freebsd-scsi
Subject:    Re: QIC tape problems on -stable (was: hanging `tar xfvR /dev/nrst0' process, can i debug it?)
From:       J Wunsch <j () uriah ! heep ! sax ! de>
Date:       1999-04-29 6:20:06
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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. ;-)


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