Defragging is unnecessary
Q I have a Mac Pro that is a few years old now and still mostly going strong but I feel like it’s starting to show its age now and I wonder if a defragging utility like Drive Genius 4 might help restore some of its original speed. I mostly use my Mac for music production and I have two 500GB drives. The startup disk is quite full now but there is still plenty of space on the other one for now. Gary Bicknell
A Disk fragmentation happens when files get split into several chunks to tuck them into the little pockets of free space left behind when other, smaller files were deleted. As your drive fills up, the available free space can end up isolated in thousands of little bubbles, so all your files get scattered to the four winds and it takes much longer to read and write them.
That’s the theory anyway. In practice, you can completely ignore disk fragmentation. OS X already uses several strategies to minimise fragmentation occurring in the first place, and will automatically defragment the most commonly used files on the startup disk. It’s true that this becomes much less effective on drives that are almost full, but the best way to fix that is to upgrade to a larger disk, not defragment the one you have. A 1TB internal hard disk costs less than £45 and will take ten minutes to install in your Mac Pro. This is cheaper than Drive Genius, and a good deal more effective.
Don’t bother defragging your hard disk. Just upgrade it.