Some things to check:
* Run "hdparm -I" on your drive. In the "Capabilities" section there is
a line "Standby timer values", for some drives this mentions a device
specific minimum. I know some drives that ignore any setting below 60
seconds.
* I also know of quite a number of drives where hdparm -B settings
override the -S settings, even if you set the -S settings after the
hdparm -B settings. You could try combinations with various values of
hdparm -B, especially 1 and 255.
Cheers,
Bart
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