Re: readahead logic and I/O errors

[Michael Tokarev <mjt@tls.msk.ru>]

Jan Knutar wrote:
> On Wednesday 15 February 2006 22:35, Michael Tokarev wrote:
> 
> 
>>after FIRST I/O error, linux continued trying reading-ahead,
>>discovering more and more failed blocks, as dmesg said.
> 
> Sorry for hijacking the thread, but on another note, is there
> anyway to tell linux to tell the drive to not bother retrying
> read errors? Would be perfect for streaming video from a
> CD or DVD. Usually video players have excellent error
> recovery themselves, which probably looks better on the
> screen than the movie coming to a grinding halt due to
> the retries.

It looks like exactly the same issue.  When you set readahead
for the drive to 0 (to disable it), the only retry which is
done is the one by drive itself.  Linux return I/O error
to the application right when drive tells so, and it's up
to the application to descide what to do next - abort
(like `cp' does), or continue next (or next-to-next)
sector etc.  I don't know how to control retries in
the drive (if it's at all possible).

/mjt