Choosing A Defragmenter
The two main criteria for disk defragmenters are manageability and efficiency. In other words, how easy is it to do what you want the defragmenter to do, and how well does it defragment the disk.
Manageability is the most obvious criterion in selecting a disk defragmenter. As a Windows system administrator, you want to be able to schedule defragmentation, remotely defragment multiple disks, set defragmentation policies, and do it all as invisibly and painlessly as possible. Ideally, disk defragmentation is a set-it-and-forget-it proposition. Since your defragmentation needs aren't likely to change much, you should be able to let the defragmenter run in the background with the minimum of attention.
Since there are significant differences in the interfaces and feature sets of defragmenters, the best way to decide which one is right for you is to try out likely products and see how easy they are to use in your environment.
Testing For Your Needs
While efficiency is important, it's not necessary – nor usually possible -- to have an absolutely perfectly defragmented disk. How close is "good enough" is defined by your needs and best determined by testing on your system.
The best way to test a defragmenter is to defrag a badly chopped up disk and compare both performance and ease of use.
Of course if you're testing several defragmenters and you want to compare apples to apples, you need to be able to restore the disk to its previously fragmented state before each test. The best way to accomplish this is to use an image copying program, like Acronis TrueImage or Norton Ghost, to make an image of the disk before running the first defragmenter; restore the same fragmented image for each test.
Most of what you're looking for will probably not be in the defragmentation function at all. Instead, you will examine how easy the program is to manage, how well it integrates into your operation, and how well it plays with the other applications you use.
Disk defragmentation is a fact of life in Windows systems. Whether you're a home user content to employ Windows Defragmenter or a systems administrator looking for a third-party product with an elaborate feature set, you need a defragmenter.
In spite of the fact that they all do the same job and they all use the Windows API to actually move clusters, defragmenters differ widely in features and their approach to defragmenting. Because defragmenting it so important to your system's health, it pays to take the time to study the available products and pick one that really matches your needs.