[gentoo-user] [OT] Manipulating a mobile external harddisk

Hi,

for storing not so often used data I bought a 2.5" external USB
harddisk.

This little beast has a very small timespan before it goes idle 
and (from the time needed to be woken up) it seems, it parks its
heads then.

The main usage of the disk to be connected to my PC from time to
time, copy some data and unconnect it again. It will never be used
with a laptop or such (accu driven machinery).

Is it advisable to try to longen the active time before the disk
goes idle to prolong the lifetime ?
Is it possible to do this with hdparm?
It is a sane idea? ;)

Thank you very much in advance for any help !
Best regards,
Meino