10 Sep
2012
10 Sep
'12
9:31 a.m.
From: Alexey Toptygin <alexeyt at
freeshell.org>
So, what drives actually need to be 'parked'? My understanding was that if
you de-energize the spindle motor and the voice coil that positions the
heads and the same time, the heads will have plenty of time to retract and
lock before the platters slow down enough for the heads to land. Was it
only needed on drives that used stepper motors for head positioning?
Either way, in what technology generation and/or time frame did the
requirement go away?
Most drives today either have springs, aerodynamic forcers (wings) or
extract
energy from the spindle motor to send the heads to the park position.
Still, landing the heads on the platters is a lot harder on them that
lifting the
heads like in the "old days". I've seen plenty of drives where the
heads were
WELDED to the platters by old head lube that had either degraded over
time or
spread from the landing zone to the rest of the platter. Not sure if
they are
still using that landing zone lube or not.
Anyway, all drives that are supposed to be parked can be assumed to handle
it autonomously when power is removed, for nearly the last 20 years.
Jon