If your disks are almost full, and you often modify or create large files (such as editing video, but see the Tip below if you use iMovie and Mac OS X 10.3), there's a chance the disks could be fragmented.

Aggressive read-ahead and write-behind caching means that minor fragmentation has less effect on perceived system performance.įor these reasons, there is little benefit to defragmenting.

This process is sometimes known as 'Hot-File-Adaptive-Clustering.'

Mac OS X 10.3 Panther can also automatically defragment such slow-growing files. With faster hard drives and better caching, as well as the new application packaging format, many applications simply rewrite the entire file each time.

Fragmentation was often caused by continually appending data to existing files, especially with resource forks.

This allows a number of small allocations to be combined into a single large allocation in one area of the disk.

Mac OS X 10.2 and later includes delayed allocation for Mac OS X Extended-formatted volumes.

With more free space available, the file system doesn't need to fill up every 'nook and cranny.' Mac OS Extended formatting (HFS Plus) avoids reusing space from deleted files as much as possible, to avoid prematurely filling small areas of recently-freed space.

Hard disk capacity is generally much greater now than a few years ago.

You probably won't need to optimize at all if you use Mac OS X.

Defrag macbook pro