[ltp] HDAPS and drives that can't park & can you park 2 drives (main+ultraybay)?

[Theodore Tso]

On Fri, Dec 28, 2007 at 12:37:47AM -0200, Henrique de Moraes Holschuh wrote:
> Otherwise, get a drive which does APS by itself (there are some, sorry I
> don't know which ones, but I believe the latest Seagate ones do so. Ask
> around), or try to replace it with a drive known to support UNLOAD
> IMMEDIATE...

The Seagate Momentus 7200.1 and 7200.2 drives both support APS as well
as UNLOAD IMMEDIATE --- and I believe some Lenovo driver are in fact
using Segate Momentus disks.

It actually makes a huge amount of sense to do APS in the drive,
because it means you don't have to constantly wake up the CPU to
sample the accelerometers to see if the laptop is falling.  So it
makes a huge difference in terms of batter life and power saving.
(The recent hdaps patch stops polling the accelerometer if the daemon
isn't running, to save power, but if you want to protect your hard
drive, the daemon has to be running, and there goes the power savings.
If you use a hard drive that has the accelerometers built in, and can
sample them in hardware without needing to wake up the main CPU, so
much the better.)

						- Ted