First, let’s deal with the notion of fragmentation and defragmentation.
Disk working speed is not uniform. The minimum is at the very center and maximum on the edges. Therefore record often begins at the “beginning”, gradually moving to the “end”. If it reaches the space occupied earlier – the entry continues to record into different place. Thus, the same data can be distributed over the disk and that the drive is not available. Thus, the disk head spends more time on finding the correct area.
Fragmentation – process of uneven distribution of information on the disk.
Defragmentation is the backwards process. Wherein all data is grouped and are completed at the same place on a disk.
In Windows-based systems FAT file system or more advanced NTFS are used. Defragmentation mechanism is not built in such systems. Which leads to the fact that every few months there is a need to defragment. The procedure can take quite a long time, but in the end, a considerable increase in performance will be achieved.
But in OS X unlike Windows a different file system is used. HFS+ which has a special function – Hot File Adaptive Clustering, or HFC. The main purpose of this component is to prevent fragmentation of disk storage.
Not to mention the fact that in modern Apple computers useSSD hard drives, that has different algorithm to eliminate fragmentation.
If you’re a Mac user, you may need to defragment hard drive under the following circumstances. You have an old Mac with an old disk drive. In such a drive files larger than 1 GB (audio, video, etc.) are stored for a long time. Such files are very susceptible to fragmentation, which previously could not be corrected automatically.
Even so, the loss of speed is not visible, so Apple never included defragmenters to the standard set of functions. However, if you still want to carry out this procedure – you can use one of the most popular application – iDefrag.