Re: 2.9test9-mm1 and DAO ATAPI cd-burning corrupt

From: Jens Axboe
Date: Fri Nov 07 2003 - 17:33:22 EST

On Thu, Nov 06 2003, Prakash K. Cheemplavam wrote:
> Prakash K. Cheemplavam wrote:
> >bill davidsen wrote:
> >
> >>In article <3FA8CA87.2070201@xxxxxx>,
> >>Prakash K. Cheemplavam <prakashkc@xxxxxx> wrote:
> >>
> >>| Sorry, I wasn't precise: The data is on the disc, as my DVD-ROM
> >>restores | the full image (md5sum matches), but the CD-RW does not.
> >>
> >>There is a problem with ide-scsi in 2.6, and rather than fix it someone
> >>came up with a patch to cdrecord to allow that application to work
> >b) The writing or reading issue mentioned above. It is a bit hard to
> >find out, whether cdrecord actually *writes* an incomplete image
> >(without using -pad), ie. throwing away the last 4096 bytes, which
> >*only* happens in non-TAO mode. The programme CDRDAO shows the same
> >behaviour. Strange enough reading this DAO written image out with my
> >DVD-ROM makes this (missing?) 4096 bytes reappear... Well, maybe I
> >should patch the image and put some other bytes instead of the 00s at
> >the end to see, whether it is a write issue, a read issue of the writer
> >or a read issue of the reader. Anyway, it doesn't sound right to me,
> >what is happening at the moment...
> So tested further: I patched the very last byts of the image and these
> are my findings:
> In DAO mode, the complete image is actually written, but the writer is
> not able to read it out! The last 4096 bytes are not read. I put the
> CD-RW into my DVD-ROM, and it reads it out completely.
> So: Is cdrecord/cdrdao making something wrong (yes, I know I can use
> -pad, but I want an *identical copy*) or has the kernel ATAPI reading
> routine a bug? (Or has my drive a bug???? Well, I need to read the disc
> out in windows I guess...)

See one of my mails from a few days ago. It's a hardware issue, some
drives need a bit of pad at the end.

Jens Axboe

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