This is just a note to self and whoever else might find it useful.
OpenSuse 11.4, Gnome.
A Western Digital 2.5 SATA hdd is set to APM = 96 both on AC and battery power, which is way too aggressive and makes the heads park constantly.
The following seems to be a solution (labeled as old, but worked as new):
Disk Power Management - openSUSE
my config file:
# Configure disk power management settings to ensure both
# long disk life and good power management.
#
# Space delimited list of disk devices this affects.
#
DEVICES_DISK_PM_NAMES="/dev/sda"
#
#
# Power management modes
#
# Powersave mode off
# Disable APM and spin-down
#
DEVICES_DISK_PM_POWERSAVE_OFF="hdparm -q -B 254 -q -S 0"
#
# Powersave mode on
# Enable APM to conservative 200 and set spin-down for 21 minutes
#
DEVICES_DISK_PM_POWERSAVE_ON="hdparm -q -B 200 -q -S 252"