What is Defragging?


Defragging, short for “defragment,” is a term used to describe a common maintenance task required by hard drives. As you store files and install applications onto your hard drive, the files may often become fragmented in their locations and take more time to locate and access. Files are deleted and others stored in their place and others on the hard drive with each computer session, which means fragmented files will always exist to slowly bog down the performance of your computer.

hard drive internals with cover removed
A hard drive with its cover removed
CREDIT: Eric Gaba/Creative Commons

The typical hard drive

Hard drives consist of spinning platters with data stored in different locations throughout its surface. As a computer writes data to the platter, it places that information in “blocks” that are ordered sequentially from one side of the hard drive’s platter to the next. The fragmentation of files occurs when data gets split between blocks of existing data or are placed far away from the rest of their respective data. The end result is hard drives take longer to read a file because the reading head has to visit multiple spots on the platter.

When you view files from My Documents or other locations, Windows will show you the file is in one folder location. But physically, the bits and pieces associated with that file are scattered across multiple areas of your hard drive’s platter.

A typical hard drive is made up of three different file structures: fragmented files, contiguous files and unmovable files. The unmovable files are typically system files that cannot be touched or altered without risking damaging the operating system. Contiguous files are the ideal type of file, data stored in a sequential order for easy reading and quick use. Fragmented files typically make up the vast majority of a hard drive and consist of hundreds of files spread throughout the surface of a hard drive’s platter, Defragging a computer puts those blocks of data back into their intended sequential order, allowing your hard drive to become more efficient and your computer faster in its function.

When to defrag

While defragging a computer used to be a rather common practice in earlier computers, it isn’t as necessary with today’s technology. Hard drives are designed to read files even faster than before, which makes the task of defragmentation not as necessary or as common of a practice. Unless a hard drive is very fragmented, you don’t necessarily need to defrag, though most industry experts will still recommend you defragment your computer at least once a month.

Solid-state drives

For owners of solid-state drives (SSD), the need for defragging is a thing of the past that will never haunt you. Solid-state drives don’t have spinning platters like regular hard drives, which means they don’t take any extra amount of time to read from different parts of the drive. With this hardware, defragging won’t offer any performance increase.

Windows 7 & 8

If you use a computer running on the Windows 7 or 8 operating systems, you don’t need to defrag your computer. Both systems are designed to automatically defragment your hard drive on a schedule, which means you don’t need to worry about performing it manually. To ensure the defrag is occurring on your computer, open up the Start menu or Start screen and type “defrag.” Select Windows’ Disk Defragmenter application and make sure the schedule is set and running.

If, when checking the Disk Defragmenter, you see your SSD on the list of drives and it’s checked, this doesn’t mean Windows is defragging the hard drive. It’s actually performing SSD-related maintenance tasks to ensure the ongoing efficiency of the drive.

Windows XP

Despite how old Windows XP is as an operating system, many individuals still use it. This version of Windows requires manual defragmentation of files due to the age and time for which the system was developed. Open the Start menu, click Run, type “Dfrg.msc,” and hit Enter. This will open up the Disk Defragmenter, through which you can defrag hard drives individually.

On XP, you’ll likely need to perform this defrag on a weekly basis, or schedule the task to run automatically using Windows’ Task Scheduler.

Mac OS

If you own a machine that operates on a Mac operating system, you won’t need to manually defragment the computer. Much like Windows 7 and 8, the operating system is designed to perform this task automatically on most small files. Sometimes defragmentation can still occur and slow down the Mac noticeably, which means you may occasionally need to run a defrag — as often as once a year.

Defrag software

Other disk defragmenter software exists beyond those offered on Mac and Windows computers. While the applications installed on your operating system will prove to be suitable for this basic task, you may want to see what files are fragmented, or even defrag system files. For more advanced functionality, you can use software like Diskeeper, PerfectDisk Pro and O&O Defrag to not only improve computer performance, but also better allocate data blocks on your computer to prevent future defragmenting of files.

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