Defragmenting Your Hard Disk

If programs starts slowly when you double-click on the program icon from within Windows, files on your hard disk may be fragmented. To store information, disks record information in storage locations, called sectors. A file is fragmented when its sectors are dispersed across your disk. In contrast a contiguous (non-fragmented) file resides in consecutive sectored locations on your disk. It takes the disk drive longer to read or write fragmented files, which makes your programs load slower. Giles become fragmented as a natural result of creating, editing, and deleting files. Fortunately, there are many different software programs you can run that defragment your disk. If you are concerned about system performance, you should run such programs on a regular basis. If you are using Windows, you can use the Disk Defragmenter program. You can also use the DEFRAG command in Windows command prompt.

How A Disk Drive Reads And Writes Information

To store information, your disk records information in storage locations on the disk’s surface, called sectors. A disk contains rows of concentric circles, called tracks, Each track is further divided into fixed-sized sectors.

To read or records information, the disk drive uses a read/write head, which is similar to a needle used by old record players. Like a record album, the disk spins past the read/write head. Unlike an album that rotates very slowly, your hard disk spins very quickly.

To read or record information, the disk drive moves the read.write head in and out, to different tracks to access specific sectors.

Assume, for example, that your disk contains a file named DCS153.jpg, which occupies four sectors.

In this case, also assume the file’s sectors reside in four consecutive storage locations on your disk.

To read the file’s contents, your disk drive locates the file’s first sector. Next, as the disk spins past the read/write head, the disk drive can read each of the remaining file sectors, one sector at a time.

How Fragmented Files Decrease Your System Performance

To read a file’s contents, the disk drive must read the file’s sectors as they spin past the disk read/write head. Some files resides in consecutive sectors, and they are called contiguous.

On the other hand, files whose sectors do not reside in consecutive storage locations are fragmented.

Unlike your computer’s fast electronic parts, such as memory or the CPU, a disk drive is a mechanical device-the disk spins within the drive and the read/write head must move in an out to access sectors that reside in different tracks. Because the disk drive in mechanical, it is much slower than its electronic counterparts. An easy way to improve system performance is to reduce the number of slow disk operations your computer must perform. Correcting fragmented files does just that. Assume, for example, that the file DCS153.jpg, resides in sectors that are dispersed across your disk. To read the file’s contents, the disk drive located the file’s first sector. After reading the first sector, the disk drive must wait (over half a revolution) for the second sector to spin past the read/write head.

Next, to read the third sector, the disk drive must first move the read/write head to the correct track, then wait for that sector to spin past the head.

Finally, to read the last sector, the disk drive must again move the read.write head, then wait for the sector to spin past. To read the fragmented file, the disk drive had to repeatedly wait for the sector to spin past the read/write head.

Such rotational delays add up, increasing the amount of time it takes to read a file which, in turn, decreases your system performance.

How Files Become Fragmented

Files become fragmented naturally as you create, edit and delete files. You are not doing anything wrong if your disk becomes fragmented. In most cases, you cannot prevent fragmented files-instead, you simply correct them. Assume, for example, that you start a letter to a fried. When you save the file to disk, your disk drive records the information within a disk sector.

Next, assume that as you are working on the letter, you have to stop typing so that you can type an office memo. When you save the memo to a file on disk, your drive will store the file in one or more sectors on your disk.

When the memo is complete, you might resume your work on the letter your previously saved to disk. As the length of your letter grows, the letter might require several disk sectors.

In this case, when your drive records the rest of the letter to disk, your drive will place the additional date in a sector that is not consecutive with the previous sector. As a result, the file containing your letter is now fragmented.

Correcting Fragmented Files

To correct fragmented files, you run a special software program that moves the information your files contain, placing the information into consecutive sectors on your disk. There are several third-party software programs you can use to defragment your disk. In addition, if you are using Windows, you can defragment your disk using the Disk Defragmenter accessory program to defragment your disk.

Defragmenting Your Disk

You can use Disk Defragmenter to defragment your disk. To run the Disk Defragmenter program, perform these steps:

1. Select the Start menu Programs option and choose accessories. Windows, in turn, will display the Accessories menu.

2. Within the Accessories menu, choose the System Tools folder and choose Disk Defragmenter. Windows will display the Select Dive dialog box.

3. Within the Select Drive dialog box, choose the drive you wish to defragment and the click “Defragment Disk”. The Disk Defragmenter program, in turn, will begin defragmenting your disk, displaying a dialog box that tells you how much of the disk it has defragmented.