Nick Craig-Wood wrote:
quoted text
> Ever since I changed to AHCI (by fiddling with random options in the
> BIOS) my external SATA drive is being run at 3.0 Gbps.  However it
> doesn't seem reliable at that - maybe the cable is too long. (It is
> probably about 80cm in total - one standard SATA cable going to the
> case and another from the case to the drive).
> 
> I read in Documentation/kernel-parameters.txt that a command line of
> 
>   libata.force=1.5Gbps
> 
> Should force all my SATA disks to 1.5 Gbps.
> 
> However this doesn't seem to work.

I cannot help with the option not working, but you might see if the drives can 
be jumpered to force 1.5Gbps, I know a number of the manufacturers have jumpers 
to force 1.5Gbps since a number of older chipsets (Via sata and probably others) 
don't properly auto-neg 1.5Gbps on a 3.0Gbps drive, and fail to work at all.

                                  Roger
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