The disk defragmenter in Windows 7 is specifically designed to defragment conventional drives, and will shorten the life of an SSD, the Disk Optimizer utility in Windows 8 and beyond correctly recognises an SSD and won't try to defragment it. The answer to your question depends on whether you're using Windows 7 or not. Defragmentation software reorganises your disk so a file’s clusters are reunited and the free space is consolidated. This reduces performance, because the disk has to move its heads repeatedly to read a file. Writing a new file can spread its fragments all over the disk. If, for example, we wanted to write a 24KB file, Windows just writes the first 12KB in the gap and the remaining 12KB after the last file.Įfficient it may be, but the more you add and delete files, the more gaps you get on your disk. Splitting the files into clusters means this space can be used by any file. If you then delete the middle file, there’s a 12KB gap of free space if we were just going to write complete files, this gap could be filled only by a file of 12KB or smaller. Struggling to get to grips with Windows 10? We have a tutorial for thatįor example, if you write three 12KB files to a disk, the first nine clusters would be used. This may seem a stupid way of doing things, but clusters mean that free space on your hard disk is used more efficiently. For NTFS the standard cluster size is 4KB, so a 12KB file is made up of three clusters. While the number of applications you install on your computer can cause some of this performance drop, the way Windows uses your hard disk is equally to blame. A file appears to you as a single object, but to Windows it’s a collection of small fragments, known as clusters, which are stored on the hard disk.

The more you use your PC, the slower it gets. Why does your hard disk get defragmented? We'll also show you how to switch off Windows' sometimes pesky Defrag tool. In this guide, we'll explain why a fragmented hard disk occurs, how to ensure your disk is in tip-top condition.

This, of course, can be a blessing and a curse. Nowadays, disk defragmenting is done in the background, most Windows PCs have it enabled by default so you don't have to think about it. We've seen in the past that defragmenting your hard disk can reduce boot time and program launch times significantly, so it's worth doing. Defragging your hard disk can make a serious difference to performance.

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