Hi all,

I was reading the book "Beginning Ubuntu Linux" by thomas keir. In this book there
is a tip given to spin down the hard disk. the author says that it will help a lot in power savings.

he gives the tip as follows

all modern hard disks come with the ability to spin down their motors to save energy.Then,when data is requested,the motors spin up again. There may be a slight delay while this happens, and some people dislike using disk spin-down because of this. However on a notebook, it can lead to a substantial increase in battery life.On a desktop system ,it's worth considering.because over the lifetime of a
computer, it can save a lot of electricity.

on terminal type
gksu gedit /etc/hdparm.conf

spindown_time=24

you can alter the value to anything you want.each time unit is 5 seconds,so 24 equates to 120 seconds or 2 minutes

when u are finished,save the file.

Reboot for the settings to take effect

Now question is how effective is this tip ???
will it lead to substantial power savings?????

It depends if you are on a laptop or a desktop, really.

A spinning HDD uses about 10 watts if I recall correctly, which is almost nothing on a desktop machine, but can make a big impact on a laptop.

Well if a average PC needs 50-100W (excluding the monitor) and if spinning down the harddrive saves 10W, you will reduce the power consumption by 10 to 20%. But if this is the harddrive where your system is installed on, there will most likely too many accesses to the disk that it wont spin down anyway. However, if you have more than one disk in your system, the second one still can spin down. And this does not only reduce the power consumption, it reduces the noise of your system as well.

Yes it will save power, but not a lot. It will reduce the lifespan of your hard drive. Because these motors are precise to the revolutions per minute. The up/down in speed will reduce your motors lifespan abit. Thu you will need to replace your hard drive. In essence you can relate it to why school buses dont turn off their motors a lot and transport trucks as it will reduce lifespan of the motor. Its a gamble.