by Dario Borghino

Created on: May 01, 2008

The operation of 'defragging', or 'defragmenting' an hard drive is a rather useful thing to do to increase, even significantly in some cases, the performance of your PC. But how does it all work?

Hard disks, even with the fastest in commerce (above 7200 RPMs) often constitute the main 'bottleneck' to the speed of a personal computer: the time to access a particular memory cell on a hard drive can be, depending on the particular technology, up to thousands of times slower than access the same amount of memory on a RAM. When the hard disk is empty, the file system is free to write the files on the hard disk to an optimal location, but after a few deletes and rewrites, what will happen is that data related to the same application will be saved into different chunks of hard disk, making data retrieval and update much slower.

The solution to the problem is defragmentation, which is an operation that rearranges all the files in a contiguous and optimal way, so to minimize the access time by the hard disk, thus reducing the 'bottleneck' effect. Fragmentation is a very delicate operation which, depending on the amount of data on the drive, can last up to several hours, so using a good and reliable program for this objective becomes something of vital importance.

In most versions of Windows, including Windows XP and Windows Vista, a disk defrag utility is embedded into the operating system. Just right-click on the hard disk icon and select 'Properties', then click on the last tab: you should be able to see, among other options, the 'defrag' button. Make sure you can leave your PC on for some time, and then start the procedure. It's often advisable not to make intensive use of hard-disk heavy programs while the operation like this is taking place, or you will risk losing data - not necessarily data that is related to the program you're using.

Depending on your hard disk speed and the amount of data you have stored, the operation could take half an hour to several hours. It is important not to interrupt the process, because the operation is generally unsafe - moreover, the whole defragmenting process is likely to start from the beginning and not resume from the last time's status.

On the Linux platform, ext2 filesystems can be defragmented with such tools as e2defrag, while ext3 filesystems can be defragmented with the 'shake' command. Interestingly enough, e2defrag also has a convenient option to virtually and temporarily, so to speak, 'downgrade' the ext3 filesystem to ext2 in order to defragment it.

Finally, Apple computers doesn't embed defragmentation utilities, for which you will need to look for a third part program such as iDefrag. On apple.com site, though, they say defragmentation is often unnecessary, and there are stories ( http://forums.mactalk.com.au/20/32660-do-you-need-de frag-your-mac-hd-answer-revealed.html ) of attempted defragmentations that strangely resulted in the opposite effect, with performance getting worse instead of better.

Learn more about this author, Dario Borghino.
Click here to send this author comments or questions.