Re: Quick question about libata and hdparm

[Jeff Garzik]

RogÃrio Brito wrote:
> Hi, Jeff.
>
> On Apr 19 2009, Jeff Garzik wrote:
> > Michael Tokarev wrote:
> > > Well, the kernel does a good job here in *almost* all cases.
> > > The problematic case is when a device has some bad/unreadable
> > > blocks/sectors.  When such a place occurs on read, libata
> > > (or whatever it is) performs several retries, each time
> > > using "less aggressive" settings - like reducing UDMA and
> > > PIO mode till the lowest possible PIO/33.  And the device
> > > stays in that mode until reboot, even if the problematic
> > > sector has been relocated.  So it'd be nice to be able to
> > > reset the mode back in such cases.
> > Do you have a log?
>
> I have a log here of libata reducing UDMA speed. I don't know if this is
> any hardware problem or not (I think not), but I do see libata
> complaining and reducing the speed of the drive.

Well, it's supposed to reduce speed in several circumstances... just not 
Michael's.  :)

	Jeff



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