What Is Fragmentation & Defragmentation?

Fragmentation is the term used to describe the unused space between the physical location of files on the hard drive. It has several causes, most notably simple usage of the computer, and can have several detrimental effects on the overall performance of your PC. To solve fragmentation, a process known as defragmentation is used. Defragmentation rearranges the files so as to leave no empty spaces on the hard drive.

Expert Insight

To understand fragmentation, one needs to consider the hard drive in purely physical terms. The hard drive is an actual object, with a limited amount of physical space in which all data must fit. Fragmentation describes a situation on the hard drive in which the physical space is not being used to optimum capacity, as well as the unused space. To look at it another way, fragmentation is several empty parcels of land in a neighborhood which are too small to construct anything on--if the parcels were combined, the space would be large enough, but as they are divided, it is not. Defragmentation attempts to bring those parcels together.

Causes

Fragmentation is primarily caused by inefficiencies in some data storage algorithms. The most common problem in these algorithms is that they circumvent a thorough scan of the hard drive to determine the best place to put the file, but instead place the file in the most readily available location. To refer to the metaphor used before, this would be like building your house so that it leaves an empty space of land between the nearest neighbors. Another cause of fragmentation is known as internal fragmentation, and is often times intentional. For ease of access, many files have what is known as slack space. Slack space is intentionally empty space in between files or inside files which allows the computer to more quickly differentiate different instructions in the code. Internal fragmentation is not generally harmful to your computer, as it is a minor file size increase applied to the original program.

Effects

The most common side effect of fragmentation is slowdown. Fragmentation causes slowdown by causing your hard drive to seem fuller than it is. Your computer has to physically search through the hard drive every time you request a file or access data, and the more space the hard drive has in use, the longer it takes for the computer to retrieve the file. A rather more serious side effect is what is known as file fragmentation. File fragmentation is a direct result of external fragmentation, and occurs when, during the process of data removal and expansion, another program writes information into the space previously reserved for the previous data. This causes the file to be saved in a different location out of necessity, and can cause the program to malfunction, function slowly or not function at all.

Prevention/Solution

The only viable solution to fragmentation is defragmentation. Defragmentation runs a comprehensive scan on the hard drive and all the files inside of it, and determines the optimal way to store your data. Although defragmentation cannot solve internal fragmentation, it will completely solve external fragmentation and can sometimes solve file fragmentation if done correctly. There are many various utilities available on the Internet, but the Microsoft line of operating systems, such as Vista, all include their own defragmentation utilities.

Advancements

Fragmentation can be damaging to your system, but it was far worse 10 years ago than it is now. Improvements on hard drive design and on the data storage algorithms themselves have helped vastly improve on the quality of file distribution. Additions to the hard drive such as the ROM cache allow programs to store temporary data on the hard drive without ever needing to take up permanent space, and rapid-revolving disk platters allow the hard drive to access files even quicker than before. Even better, techniques have been developed that allow hard drives to attain ever greater data density, allowing data to take up even less room and therefore fitting into smaller spaces.