Re: Linux, ISOFS, multi-extent files: what's the status?

Volker Kuhlmann wrote:
> On Sun 10 Jan 2010 10:15:10 NZDT +1300, Bill Davidsen wrote:
>
>   
>> There was another error having to do with reading data at the end of an 
>> image. Due to read ahead settings a read past end of data occurred and the 
>> (valid) partial data was not returned to the user program. Might that be 
>> what you are remembering?
>>     
>
> Thanks for mentioning it. Since the mid-90s the kernel produces I/O
> errors reading the last blocks of an ISO image from actual disk because
> of a read-ahead function. Turning off read-ahead is not sufficient to
> prevent this error, turning off DMA is also necessary (presumably that
> has its own read-ahead too). This problem because suddenly worse again a
> few years ago when DVDs arrived (larger block size, larger read-ahead). 
> I can't say whether it's ever been fixed completely, I always use a
> workaround for my own disks, but haven't seen it much on other disks any
> more.
>   

I have just turned down readahead in blockdev and my issues have gone 
away, but like you I don't see it much if a while.


-- 
Bill Davidsen <[email protected]>
  "We can't solve today's problems by using the same thinking we
   used in creating them." - Einstein


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