starting from this site
https://bugs.launchpad.net/ubuntu/+source/acpi-support/+bug/59695
here you'll find a workaround:
https://bugs.launchpad.net/ubuntu/+source/acpi-support/+bug/59695/comments/14Problem::
- Frequent HD clicks -- more than one per 3 minutes while idle, louder than the typical access sounds. Often more than twice per minute. On some disks, the click is very quiet
- Early hard disk failure never stay parked, due to very frequent disk activity. Thus this cycle occurs often, thus wearing out the drive, and any comparative benefit is negligible (whereas, if the-- some disks are cut down to less than a year of actual uptime.
- Drives are spec'd to a limited number of these cycles. (600,000 is the most common, although some may be spec'd higher or lower).
- The OS not setting disk APM variables according to current disk access pattern.
So ... check your cycles::
Solution::
Here is how I permanently fixed it:
1) make a file named "99-hdd-spin-fix.sh". The important thing is starting with "99".
2) make sure the file contains the following 2 lines (fix it if you have PATA HDD):
#!/bin/sh
hdparm -B 255 /dev/sda
3) give to it execution rights
chmod +x 99-hdd-spin-fix.sh
4) copy this file to 3 locations:
/etc/acpi/suspend.d/
/etc/acpi/resume.d/
/etc/acpi/start.d/
Voila! After that the HDD never spins down on power (looks like it actually spins down on battery at modest rate).
Sorry if the instruction is too detailed, no offense.
Solution at a glance::sudo gedit /tmp/99-hdd-spin-fix.sh
write inside the file the following lines:
#!/bin/sh
hdparm -B 255 /dev/sda
sudo cp /tmp/99-hdd-spin-fix.sh /etc/acpi/suspend.d/.
sudo cp /tmp/99-hdd-spin-fix.sh /etc/acpi/resume.d/
sudo cp /tmp/99-hdd-spin-fix.sh /etc/acpi/start.d/
sudo /etc/init.d/acpid restart