Comment 87 for bug 59695

I have _very_ big doubts that any hard disk (even a laptop one) is supposed to spin down after only 20..30 seconds of idle time. If you can sustain this "it's supposed to be that way" with an official manufacturer specification or statement I would greatly apreciate it.
As far as I know, repeated on-off cycles are more stressing to the device than simply letting it run.

Searching about this spinning problem on Western Digital's site I found that some of their drives spin down after 10 minutes of inactivity. This is by far a better default that the one I found is set by the OS's power management scripts. If you look above at my experiment you will find that those scripts execute hdparm -S4 which translates in 20 SECONDS of inactivity before spinning down. This IS insane comparing with 10 minutes. Even more, on the same manufacturer's site I found a document where they say that respinning up a harddisk takes a lot of power (the current peaks at about 1A) which means that if it's needed/done too frequently it basically nulls any power economy you would make by spinning the drive down in the first place...
WD knows this and this is why on some of their products the idle timeout is set to 10 minutes and not to 20 seconds. And I am very sure that the other manufacturers are also aware about this and will not set impossible timeouts that actually do not help them obtain a better medium power consumption. After all, the whole point is to spin the disk down when the probability that the disk will not be needed again too soon is high enough.