There is a popular myth online and in some gaming communities that PlayStation 3 hard drives need to be defragmented, just like a Windows PC computer hard drive. But it is just a myth. File fragmentation happens when software, like a computer operating system, moves files around the physical hard drive and places them together where file access by the operating system is faster. A defragmentation program, such as the Defragmenter program that comes with Windows, puts these fragment files back in order, hence speeding up your disc.
Linux and Mac OS computers do not come with defragmenter utilities. That's because they handle files differently than Windows and essentially take care of file fragmentation as it happens. PlayStation 3 hard drives handle adding and removing files the same way.
PlayStation 3 handles files just like Linux, in a format called CellFS, so your game files are never fragmented in an appreciable sense, as they would be if it ran on a Windows platform.
Since there is no fragmentation, there is nothing that needs to be done to care for the hard drive.