Prosoft Engineering's Drive Genius ($99) offers a range of features in addition to more powerful versions of the features offered by Disk Utility. Drive Genius also comes with a user-friendly interface that has easy-to-locate explanations of its features and excellent documentation.
Like Disk Utility, Drive Genius can check drives and partitions for directory corruption or damage, as well as verify and repair file permissions. When Drive Genius encounters a corrupted directory, it offers two options:
- Repair essentially takes the same approach as Disk Utility, attempting to repair the existing directory information by looking at the actual sectors of the drive and adjusting the directory information accordingly
- Rebuild ignores the original directory and creates a new one, based solely on the layout of data in the sectors of the disk. If the directory structure of a disk or partition is so badly damaged that tools such as Drive Genius or Disk Utility can't match the directory to the layout of data in the sectors of the disk, the next step in attempting to recover the disk and its data is to build a new directory from scratch by examining the actual data. Rebuilding stands a greater chance of recovering disks that have a severely corrupted directory.
Like Disk Utility, Drive Genius can check and display the S.M.A.R.T. status of a drive, but it also offers additional features for ensuring that a drive is physically functional. The Scan feature scans the magnetic platters of a hard drive and checks that each sector or block is capable of having data written to it and read from it. This process occurs automatically when a drive is formatted; bad blocks (those that can't reliably store information) are mapped out of the directory so that data will not be written to them. Drive Genius allows you to repeat this scan at a later point to ensure that no additional bad blocks have developed; if the disk has bad blocks, Drive Genius maps them out.
Drive Genius also can check the drive and individual files for fragmentation. Although disk and file fragmentation isn't a major issue with modern file systems such as Apple's Mac OS X Extended or Microsoft's NTFS, fragmentation still can occur. You can regain some performance by ensuring that the pieces of data that make up a file are located in sectors physically adjacent to each other on the drive. You can also benefit by grouping similar types of files (such as system files) in one section of the drive. However, unless you're working with a nearly full drive and/or very file-intensive tasks, you're not likely to notice much difference after defragmenting a drivewhich Drive Genius can do after checking the degree of fragmentation.
Version 3 of Drive Genius introduces a feature called Drive Pulse, which runs in the background and continuously monitors the state of your hard drive(s). You can choose to monitor the physical (S.M.A.R.T.) status of the drive, the directory structure, and the degree of fragmentation. When potential problems begin to arise, Drive Genius can alert you, allowing you to take corrective action before an issue becomes a serious problem.
Like Disk Utility, Drive Genius offers a secure erase feature, called Shred. Its functions are essentially similar to those offered by Disk Utility, although you have the choice to do a one-pass erase in which all sectors are filled with random data (more secure than Disk Utility's option for filling them with zeros). You also can choose a three-pass erase, which is a compromise between the speed of a single pass and the security of seven passes.
One of the most useful Drive Genius features for consumers is DriveSlim, which allows you to reclaim disk space by searching for potentially unneeded files on your hard drive. You can choose to look for files exceeding a specified size or that haven't been accessed for a specified period of time; other searches find duplicate files and cache or temporary files that have been used recently and are most likely no longer needed. Many applications and system processes use such files to speed up certain tasks, but may not delete them when they're no longer needed.
Another option is to remove parts of applications that you don't need. For example, most applications and system components come with language localizations that allow them to display menus and information in multiple languages; others ship as universal binaries that can function natively on today's Intel Macs and older Power PC Macs (as well as in 32-bit or 64-bit processing modes). If you'll only use your Mac in one language (or even two or three), and you won't be sharing applications with other types of Macs, you can use these features to reclaim a fair amount of space.
Like Disk Utility, Drive Genius can mount, eject, format, partition, and duplicate disks. Drive Genius also offers performance-test features and manual editing of a drive's sector information. (Only experienced technicians should attempt this type of editing, and most users won't need it anyway.)