[ltp] Does hdaps [APS] work on non-Thinkpad hard drives?

linux-thinkpad@linux-thinkpad.org linux-thinkpad@linux-thinkpad.org
Sat, 5 May 2007 13:29:58 -0400

On Saturday 05 May 2007 11:50, Henrique de Moraes wrote:
> Unload Immediate is not a common feature on disks yet. =A0And most HD
> techsheets are really pathetic, so you will have to, e.g. limit yourself =
> Hitachi disks, and get their full tech spec sheet in their technical
> library. =A0It describes *all* HD commands, so you find out right away wh=
> it supports or not.
> Besides, if you are going to use it, you also want the disk to survive at
> least 300K unloads... =A0I really recommend hitachis for this, as they
> survive 600K unloads.

You are correct. Datasheets are very unreliable and are missing many=20
specifications. It seems like most of them are written by lawyers or=20
marketing people.

> Unload immediate *unloads* the heads, which is not parking. =A0It *lifts*
> them off the platter and secures the head assembly so that they cannot hit
> the platters even under a big-G shock.
> Not all HDs "parks" head by unloading. =A0And even those which do won't
> unload them FAST (without a cache flush), which unload immediate does...

Now that makes sense. Thank you for that clear explanation. And I take it=
there are no hard drives that incorporate HDAPS in the hardware, correct?=
That is, a hard drive that does not need software to tell it to unload by=
having it's own motion detection.