How to Defrag Your Hard Drive

Defrag for Other Operating Systems

As you might suspect, operating systems such as Mac OS and Linux use different file management systems and have different requirements in terms of defragmentation.

The operating system for Apple's Macintosh computers doesn't include a built-in defragmentation application, although third-party utilities are available. According to Apple, Mac OS is designed to reduce fragmentation by writing new data to larger open areas of the disk. Smaller segments, such as those left over when a file is deleted, are only used when necessary. Macintosh software developers are taking advantage of faster hard drives to eliminate fragmentation by always writing complete files to the disk rather than adding data to existing files. Mac OS (10.3 Panther) and later versions defragment files on an ongoing basis, making batch defragmentation unnecessary.

As for Linux, there are two major reasons defragging is less of an issue. First, Linux doesn't store files in order, so there's often room to append data to an existing file in its current location. Linux also places the disk reading head at the center of the platter. Unless a file is fragmented to opposite sides of the disk, the head can reach multiple clusters quickly. Linux isn't, however, immune to fragmentation, particularly when a disk nears its maximum capacity. The bad news is, when the disk is nearly full (more than 75 percent of space used), it becomes more difficult for a defrag utility to operate effectively. So, by the time a Linux disk becomes fragmented enough to slow things down, it's difficult to solve the problem. For many users, this paradox provides a reason to defragment Linux hard drives on an ongoing basis.

Third-party defrag applications are available for all operating systems. In addition to defragmentation, many of these utilities provide additional capabilities, such as:

  • Simplified scheduling
  • Background defragmentation
  • File storage optimization/fragmentation prevention
  • Optimization of other system elements such as the registry
  • Permanent removal of sensitive files
  • Elimination of cookies and temporary Internet files

But what about non-mechanical disk technologies such as solid state or thumb drives? Some computer manufacturers are already putting them in laptops and other electronic devices. Do those need to be defragged, too?

The reason defragmenting a hard drive can increase computing speed is because the drive uses moving parts (the disk and drive head) to access data. A solid state drive has no moving parts, so retrieving any specific bit of data requires the same access time no matter where the file clusters are stored. In fact, some experts claim that defragmenting a solid state drive may actually be harmful. Solid state memory can be written and overwritten many times, but there is a limit. Each time data are written to a bit of memory, its lifespan is decreased slightly. Therefore, continuously defragmenting a thumb drive could hasten its demise with no real benefit.