Disk defragmentation is all about maintaining—or restoring—strong system performance. If you don't perform periodic defragmentation, free space and new or frequently updated files can become increasingly fragmented, requiring extra physical actuator movement to read and write files and leaving you twiddling your thumbs, waiting for your computer's disk activity LED to go dark.
In this comparative review, I take a look at three prominent enterprise disk-defragmentation products—Diskeeper's Diskeeper 10, Raxco Software's PerfectDisk 7.0, and Winternals Software's Defrag Manager 4.0—to determine which fares best in terms of features and functionality. (An additional product, O&O Software's O&O Defrag 8.0, was originally included in this review, but unfortunately it ran into unforeseen conflicts with my test system, and I was forced to remove the software from my comparisons. For more information, see the Web-exclusive sidebar, "OOD Offers Another Alternative," http://www.windowsit pro.com, InstantDoc ID 50063.)
Auto Defrag
Manually initiated disk defragmentation still has its place—for example, just before loading a large amount of new data or many new files to a volume—but most of the time, you simply want your users to focus on their work, without needing to worry about the performance of their desktop and portable systems. Both the IT pro and the user merely want those systems to remain as speedy as they were when they were new.
The three defragmentation products in this comparative review are designed to make disk defragmentation an automatic, worry-free process for you and your users. All the products use the Windows file system APIs to safely move files. Using various mechanisms, these products run periodically to keep storage volumes defragmented. The products' vendors take varying views on the need to consolidate free space. Free space is almost never completely consolidated into a single contiguous space. Required locations for certain system files, as well as the inability to move others during normal system operation, generally leaves free space in several chunks—even in best-case scenarios. With a defragmentation program running at frequent intervals, files that are fragmented when written will soon be defragmented anyway.
To make ongoing defragmentation as efficient as possible, most of the products offer a way to identify and group rarely changed files, creating a section of the volume that won't fragment quickly. Similarly, frequently accessed or updated files are grouped for most efficient access and subsequent defragmentation.
Testing
Measuring improvement of system performance can be difficult. Instead, in my tests, I measured the structural improvements that each product created—in other words, each product's ability to reduce the number of fragmented files on the volume. Because some products have worked better in the past than others, with small amounts of free space on the volume, I tested each product twice, once with 5 percent free space and again with 20 percent free space.
For testing, I used an 80GB volume on an Intel EM64T-based system running Windows Server 2003. I created a highly fragmented volume that the Windows fragmentation analyzer said was 30 percent fragmented, with thousands of fragmented files and tens of thousands of fragments. Using a random number generator to select files, I deleted files from this volume to reach a desired amount of free space. I used Symantec's LiveState Recovery Advanced Server Suite 6.0 to create and restore the volume images, and I rebooted the server before each test iteration.
I also restored a clean version of the server's boot volume before installing each product for testing. For testing, I ran a manually initiated defragmentation of each volume, using the products' default settings. I recorded the number of fragmented files and the number of excess file fragments at the program's completion, as well as the time it took to complete.
The products' default options are roughly similar. Each program places the highest priority on defragmenting files. The products differ most in their treatment of free space. Diskeeper, with its performance oriented philosophy, realizes that good system performance doesn't require a complete defragmentation in the initial run and therefore makes free-space consolidation a low priority. Winternals' Defrag Manager takes the middle road, and PerfectDisk more aggressively consolidates free space. Table 1 shows a summary of my test results.
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