Tim writes:

Hmm, I'll have to have a listen out for what my laptop does.  I can well
imagine laptops having an emergency shutoff, seeing as some of them use
motion detectors to protect drives against bangs.

But my external drives seem to make the same loudish bang when they put
themselves to sleep, compared to losing power.

That seems to be rather broken. I can't claim to be a big HD expert, but having the platters stop spinning with the heads still flying over the platters will crash the heads, and permanently ruin the drive, so the heads must return to their parking position before the drive stops spinning.

In an orderly shutdown, the heads get returned to their parking spot, during ordinary course of business, then the power goes off.

The "clunk" is when the drive detects a loss of power, and it's using its reserve power, in some capacitor or something, to just yank the heads out of the way, ASAP, to avoid a head crash. It's got limited power, so it can't waste milliseconds bleeding it off by moving the heads slooowly to their parking spot. So, they get yanked off the platter, ASAP. And the clunk is the heads slamming against the end stop. Which is preferrable to having the heads crash on the platters.

If your drive knows it wants to go to sleep, it should be moving the heads normally into the parking location, instead of just cutting off its own power, and have the heads go into an emergency retract.


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