acd(4) and maximum read block size

[Angka H. K.]

I have concern about it but my case is different.

I have a disk that burn using 6.1-current and it burn good no error with 6.1.
But when I read it on 7.0 it produce error ("i am not quite remember but
something with big..., like reading error sector"). The disk still readable
but the access is slow.


On 4/22/06, Ulrich Spoerlein <uspoerlein at gmail.com> wrote:
>
> Søren, group,
>
> I'm working on some improvements for recoverdisk[1] to handle optical
> media
> better. I found it an invaluable tool for recovering old CD-Rs. It also
> helps with newer DVDs, when your drive sucks wrt. error recovery.
>
> recoverdisk tries to read in 1MB, 64kB and SECTORSIZE chunks. This has
> the obvious drawback, that it can't really handle audio CDs or mode 2
> CDs with a sectorsize of 2352.
>
> While this is easily fixed, the acd(4) driver seems to allow no reads
> greater than 128kB *for audio CDs*. While this is also not terrible, it
> results in roughly 700 error messages per CD, as all the 1MB (1046640
> bytes, more precisely) chunks will fail.
>
> A side note: Accessing audio CDs via atapicam and dd(1) is completely
> impossible. Is the SCSI subsystem limited to multiple-of-512-blocksizes?
>
> [1] /usr/src/tools/tools/recoverdisk
>
> Ulrich Spoerlein
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>