A file that may have been splattered all over the platter is placed in a contiguous band, so loading apps and files speeds up. Since the moving read/write head has to travel all over the width of the platter to load files or applications, the entire system seems to slow down.ĭefragmentation is the process of reading files, then rewriting them so that single files are written on the spinning platter in such a way that the drive head doesn’t need to move back and forth. However, the data can’t automatically migrate itself to the outer edges of the platter to fill in available space, so after a lot of reads and writes have been performed, there are small gaps where big files can’t be written, so they are stored in places all over the drive platter. As a result, new data is generally written on the outside of the platter, moving in towards the center as more data is stored over the years. As you’d expect, although the platter is rotating at a fixed rate, the outside edge of the platter is moving faster than the inside edge. HDDs use a magnetic read/write head to access a fast, rotating round platter, typically spinning at 5,400 or 7,200 revolutions per minute. So never defrag a SSD, OK? For more background on the difference between SSDs and HDDs, check out this recent Tech 101 post on the Rocket Yard.ĭefragging is short for “defragmentation”, the process of organizing the files on a hard disk drive to optimize how it reads and writes those files. Note: SSDs do not use a spinning platter to store data instead, data is stored and accessed from flash memory. Attempting to defrag an SSD or Fusion Drive is actually dangerous to the drive, as it can reduce its lifespan. In this Tech 101, I’ll talk about why defragging is largely unnecessary on a Mac and how to do it if you’re one of the users who may need to defrag a HDD. Well, they won’t find any command or utility to let them do that on a Mac. After a few years, all computers seem to slow down somewhat, and new Mac owners might think back to the solution that they turned to on those Windows computers - defragging the hard disk drive (HDD).

With sales of Macs reaching an all-time high, there are a lot of new users who are coming over from the world of Windows PCs.

Defrag a mac hard drive