> On Fri, 23 Oct 1998, Andre M. Hedrick wrote:
>
> > The tape driver defaults to "ATAPI overlap supported" and is not flag
> > tested and updated. Since the "HP COLORADO 5GB" reports that this is
> > not supported hardware via the logs and the driver thinks that it is
> > support, here is the first suspect in causing timing faults.
>
> I've just eyeballed the ide-tape sources. It looks like DSC is most likely
> the culprit of the problems we've been seeing with our tape devices.
> Switching this off should *hopefully* fix it. The programmer who left in
> the comments about it seemed to imply that DSC should be replaced with the
> newer ATAPI overlap protocol for all new IDE tape devices.
I am positive that Gadi did this intentionally as a crumb trail.
The point about the "ATAPI overlap protocol" that is missed making is as
follows. The "HP COLORADO 5GB" ide-internal-tape drive that
I am using is about 4 months old, thus I would have considered it new.
It reports in the debugging that it (ide-tape-drive) can not do the
"ATAPI overlap protocol". However it is set by default enable in the
ide-tape.c driver code. Since the assumption that everything is now
"ATAPI overlap protocol" ready/capable is faulty, I am looking a method of
extracting the "debugging info" and testing the hardware. I am also
interested in auto-enabling DMA transfers, since the tape-drive reports to
support DMA mode 2 multi-word but is not enabled by default.
I am now running a second tape-backup test with the overlap disabled
under 2.1.126-pre-2 plus other patches of mine that have not effect on the
ide-tape driver. It appears that it is now fully functional again and no
crashes.
> * ATAPI overlap is likely to be supported in most new ATAPI
> * devices, including new ATAPI cdroms, and thus provides us
> * a method by which we can achieve higher throughput when
> * sharing a (fast) ATA-2 disk with any (slow) new ATAPI device.
This above describes the exact nature of the device pair on ide1.
A DMA mode 2 capable ide-tape device at 'hdd' and a PIO 0 limited
IOmega IDE-ZIP drive with fw-revision 23.D.
Cheers,
Andre Hedrick
The IDE-FNG for Linux
The APC UPS Specialist for Linux
http://www.dyer.vanderbilt.edu/server/udma/
http://www.dyer.vanderbilt.edu/server/apcupsd/ SUSPENDED
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