Fragmentation happens when your operating system cannot or will not allocate enough contiguous space to store a complete file as a single unbroken unit. Instead, the system puts parts of a file in the gaps between other files. Generally, those gaps are there because they once held a file that the has since been deleted. Sometimes, the gaps are there because the operating system allocated too much space for a file in the first place and never filled it, leaving empty space at the end of a file. Larger files and a greater numbers of files also contribute to fragmentation and the performance loss it causes. Defragmentation is aimed at resolving these issues.
Defragmentation is a normal system process that reduces or eliminates fragmented files. It does this by physically reorganizing the contents of your hard disk to store the contents of each file close together and in a contiguous manner. At the same time, the process attempts to create larger regions of free space using compaction to impede the return of fragmentation. Some defragmentation software also tries to keep smaller files within a single directory together, as they are often accessed in sequence by the operating system. The movement of the hard drive’s read/write heads over different areas of the disk when accessing fragmented files is slower, compared to accessing a non fragmented file in sequence, without moving the read/write heads. Putting the files back together again is what yields the performance boost. The drive heads don’t have to move as often or as far, saving time.
On your Windows 7 system, start the defragmentation process by going to Start → Control Panel → System. Under the Administrative tools section, click on “Defragment your hard drive.” In the panel that opens, select the drive or drives (use the Current Status section) that you wish to defragment. Then click on “Analyze disk.” Windows will then analyze the percentage of your disk that is fragmented, and recommend whether or not you should run the defrag process. If Windows says to defragment the disk, click on “Defragment Disk” and let it run. It can take from a few minutes to a few hours to complete the process, depending on how long it has been since you last defragmented.
You can also schedule regular defragmentation sessions using the Control Panel defrag panel. Because the process is very disk-intensive, performance will be degraded slightly when the process in running. If you choose to schedule your defragmentation sessions, you may wish to select a day and time when you won’t be using the system, like the first day of every month a 2:00 in the morning. The same is true for manually controlling defragmentation. When scheduling, you would probably be safe to set your system to defragment once a month. Your files will rarely become badly fragmented in less time than that.
It is probably a good idea to schedule defragmentation since it is something we normally don’t remember to do. Plus, running defrag once a month will keep the process from taking to much time when it does run, since your files will not have had a lot of time to become fragmented.