Hdparm is a performance tool for your Hard Disk (SATA/IDE).
# pacman -S hdparm
To get information about your disk, issue:
# hdparm -I /dev/sda
Reading speed MB/s
To measure how many MB/s your Hard Disk (IDE/SATA) can read:
# hdparm -t --direct /dev/sda
Writing speed MB/s
$ sync;time bash -c "(dd if=/dev/zero of=bf bs=8k count=500000; sync)"
Don't forget to ctrl+c and rm bf after that.
Parking your HDD
If your HDD is clicking many times, the kernel is parking the reading head of the HDD. This happens often on laptops (2.5" IDE HDDs). If it happens too often, it could damage your HDD.
This will just park the reading head when you shutdown:
# hdparm -B254 /dev/sd
Default value is -B128. An average value could be -B199 if it's parking too often.
Tips and tricks
KDE => 4.4.4 and hdparm
To stop KDE version 4.4.4 or greater from messing around with your (manually) set hdparm values, enter:
# touch /etc/pm/power.d/harddrive
and you should be done.