Linux-kernel mailing list archive 2000-01,: corrupted data with ide-scsi emulation

# corrupted data with ide-scsi emulation

Tuukka Toivonen (tuukkat@ees2.oulu.fi)
Tue, 4 Jan 2000 09:35:55 +0200 (EET)

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First I create an iso9660 fs image (having the file size of xxx
kilobytes) and md5sum it.
Then I burn it to a CD-R disk.
I want to see if the CD is ok, so I do:

dd if=/dev/cdrom bs=1024 count=xxx | md5sum

Which gives wrong md5sum! If I run the above command several times, it
always gives a different result meaning that there's some problem while
reading the CD-R.

However, if I do
dd if=/dev/cdrom bs=1024 count=xxx of=image.iso
md5sum image.iso
I *always* get the right result. So could this be a kernel problem instead
of hardware problem?
Also, if I do
dd if=/dev/cdrom bs=1024 count=xxx | cmp - original.image
it succeeds also always.

Also strange is that some (maybe 20%) of CD-R disks work fine and give
correct md5sum even if running md5sum in pipe.

I have had never problems while using the CD-R disks normally mounted,
except when I tried to set unmaskirq to on with hdparm, which gave lot of
read errors.

This is Mitsumi CR2801TE cd-r drive, and I have tried really many of 2.0.x
kernels as well as 2.2.13 which all give the same result.
The cd-r drive is in /dev/hdc, my hard disks are in /dev/hda and hdb and
/dev/hdd is not attached to anything.

    --
    | Tuukka Toivonen <tuukkat@ee.oulu.fi>       [PGP public key
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    | Studying information engineering at the University of Oulu
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- Next message: Ingo Oeser: "vm_operations (was: Re: release not called for my driver?)"
- Previous message: Magnus Danielson: "Re: Super Lint (was: Unexecutable Stack / Buffer Overflow"
- Next in thread: Jason Bishop: "Re: corrupted data with ide-scsi emulation"
- Reply: Jason Bishop: "Re: corrupted data with ide-scsi emulation"