Re: cdrom read errors.
On Fri, Jan 24, 2003 at 10:53:41PM -0600, Jason Pepas wrote:
> hi all,
>
> investigating cdrom read errors.
>
> - error only occurs at the very end of the disc
> - error occurs wether using dd or cat
> - error occurs wether using hdparm or not
> - error occurs wether media is mounted or not
> - resulting iso seems just fine.
> - error seems to occur randomly among discs, but consistently for a single
> disc.
Some CD-ROMs have a bug which prevents them from reading the last
sector. I have a CD-ROM which barfs 2 sectors before the end of the
discs, repeatably, but only on some disks, using readcd - which is
handy, because of the sector info and stuff you get when it hits an
error. For a given CD, it always barfs on the same sector.
The iso SEEMS fine; I THINK that when a CD is written, blank sectors
are added to the end to allow for this sort of thing.
Another possibility might be that a build-up of crud on the sled slide
bars is preventing it moving freely at the end of its travel. This
would tend to show up on longer CDs, and readcd would not barf
consistently on the same sector.
Pigeon
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