Goswin von Brederlow wrote:

Michael Evans [off-list ref] writes:
  

quoted

Why doesn't the kernel issue a pessimistic alternate 'read' path (on
the other drives needed to obtain the data) if the ideal method is
late.  It would be more useful for time-sensitive/worst case buffering
to be able to customize when to 'give up' dynamically.
    

That is a verry good question. I look forward to seeing patches for this
from you. :) I think it isn't done because nobody has bothered to write
the code yet but maybe I'm wrong and it would make the code too
complicated.
  

This is probably more complicated than allowing a timeout to be set at 
the MD layer or block-device layer, isn't it?

Which would be just as good I think.

Is it possible to cancel a SATA/SCSI command that is being executed by 
the drive?
(it's probably feasible only with NCQ disabled anyway, but it's easy to 
disable NCQ)


It's a pity we have to rely on TLER, this narrows the choice of drives a 
lot...