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.

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.

Diskeeper 10
Diskeeper 10, formerly a product from Executive Software, is the current version of a disk-defragmentation suite of products that debuted in the era of Windows NT 4.0. Deeply aware of disk-defragmentation concerns early in the game, Executive Software worked jointly with Microsoft to develop Window's MoveFile API, which made safe disk defragmentation possible. Products in this suite start with the reasonably priced Home Edition and include versions for workstations and servers, as well as an administrative console for centralized management.

Defrag features. Diskeeper's algorithms focus on the goal of disk defragmentation—improving system performance—and aren't primarily concerned with creating a perfectly defragmented disk. Rather than make an urgent effort to pretty up the final map, Diskeeper 10 often leaves a few fragmented files on a volume. Diskeeper's Comprehensive Defragmentation option spends more time defragmenting free space than the Recommended Defragmentation option. However, for Diskeeper, "comprehensive" is a relative term; this option consolidates free space progressively over multiple scheduled runs. This option is available only for regularly scheduled defrag jobs.

Intelligent File Access Acceleration Sequencing Technology (I-FAAST) is a new feature in Diskeeper 10. I-FAAST continually monitors volume activity and performance over time, moving the most frequently accessed files to locations on the volume where the system can access them most rapidly. I-FAAST is included with Diskeeper's Professional Premier Edition and the two Server editions.

Diskeeper 10 runs as a service, monitoring system activity and performing automatic system idle-time defragmentation. Diskeeper 10 is intended to be placed into one of several "Set It and Forget It" scheduled modes; the product also supports standard time-of-day and day-of-week scheduling modes.

I particularly like Diskeeper's unique I/O Smart feature, which listens for I/O requests from other processes, pausing defragmentation and giving priority to other processing. According to Diskeeper, I/O Smart lets defragmentation occur in the background without degrading overall system performance, even on busy file servers.

The number and size of volumes Diskeeper 10 will defragment is a key difference between the various editions. The number of simultaneous volumes defragmented ranges from one to unlimited, and the largest supported volume ranges from 768GB to unlimited.

Management features. Diskeeper's new Administrator Edition is a console management program that lets you schedule and manage Diskeeper installations on servers and workstations across your network. Administrator Edition is a separate product and doesn't include the defragmentation engine.

Administrator Edition might be aptly renamed Diskeeper Wizard Central. You perform most administrative tasks through a guided, wizard-like procedure. This structure is a bit cumbersome to use. (I prefer a heavy use of context menus and tabbed configuration windows.) Nevertheless, Administrator Edition makes it easy to manage Diskeeper 10 across the network—for example, adding and removing managed computers, deploying different versions of Diskeeper to your systems, and setting schedules and defining alerts.

Testing. To begin my testing, I installed Administrator Edition on an XP Professional Service Pack 2 (SP2) system. The software required a Microsoft SQL Server or MSDE database for data storage. I took the MSDE option, downloading a Diskeeper-specific installation package from Diskeeper's Web site. I installed the Professional Premier Edition to the management console system, and installed the Server Edition to a fresh installation of Windows 2003 SP1, running a supplied .bat file to open ports through the firewall that the administrator uses. Figure 1 shows Diskeeper's after-defragmentation display. See Table 1 for the comprehensive results.

I found Diskeeper easy to use, both in standalone mode and when using the Administrator Edition console. I valued the I/O Smart feature and its ability to pause background defragmentation in the presence of other I/O activity on the system.

PerfectDisk 7.0
PerfectDisk comes in both Workstation and Server versions. Both support Windows 2000 and later, and both offer the same feature set, but neither come with volume size or count limitations.

Defrag features. The Raxco philosophy is that a disk is either fragmented or not fragmented. The software strives to defrag both files and free space completely—hence the name PerfectDisk. PerfectDisk runs as a service. PerfectDisk's file-placement strategy, called Smart Placement, groups recently modified files near the free space and places rarely modified files at the beginning of the disk. You can set the age of both groups. Although Smart Placement is the default method, PerfectDisk also supports a faster Defragment Only mode that skips the file-movement and free-space consolidation steps.

PerfectDisk's boot-time defragmentation option defragments system and NTFS metadata files, and if necessary, relocates and resizes the Master File Table (MFT) for optimal performance. PerfectDisk reports on its activity by creating a log file and optionally by logging error and informational messages to the System event log.

Management features. PerfectDisk is distributed in Microsoft Installer (MSI) packages, which you can deploy through such methods as direct installation, automated deployment with Group Policy, Microsoft Systems Management Server (SMS), and third party deployment tools. PerfectDisk supplies a Group Policy administrative template that lets you schedule and configure PerfectDisk through Group Policy.

The PerfectDisk console runs in Standalone or Network mode. Network mode, which Figure 2 shows, requires administrative authority and lets PerfectDisk connect to other PerfectDisk clients for management purposes. PerfectDisk's Network Configuration Management Wizard asks you to select from a group of computers to manage from AD, as well as from those that appear in the Browse list, before setting the schedule and defrag options for the job. Although using the console to schedule a defrag for a group of computers is easy, it's a little cumbersome to go back and see which computers are grouped and when they're scheduled. You can also set configuration options (including defrag schedules) in a config.ini file and deploy them at installation time. When you install clients in Standalone mode, you choose whether to make the GUI available, thereby permitting users to manually defrag their systems.

If a computer isn't turned on at the scheduled defrag time, you can configure Perfect-Disk to wake it from Standby or Hibernation modes, to defrag when the computer starts up again, or to simply skip to the next scheduled defragmentation run time. A threshold-based defragmentation option lets PerfectDisk skip a scheduled defrag run if PerfectDisk's Analyze function finds that disk fragmentation is less than a percentage that you specify.

Testing. PerfectDisk is easy to install and operate. As you can see in Table 1, PerfectDisk performed effective defragmentation runs. Curiously, it did slightly better on the 5 percent free space volume than it did on the 20 percent free space volume.

PerfectDisk 7.0 is an effective, easy-to-use defragmentation utility. Although it lacks built-in push-deployment features, its auto-update feature and Group Policy and MMCbased management features will simplify management throughout your organization.

Defrag Manager 4.0
Defrag Manager 4.0 has an interesting architecture: It's available in one edition that works on all Windows versions since Win2K, as well as on NT in its offline modes. Defrag Manager has no volume size or volume count limitations.

Defrag features. Defrag Manager takes a three-phase approach to volume defragmentation. The first phase is a quick pass to defragment most files, the second phase more aggressively defragments files, and the third (optional) phase aggressively consolidates free space. Scheduled use of Defrag Manager defragments all volumes of a target system, although you can use the Command-Line Interface (CLI) locally to defrag individual volumes on demand.

Defrag Manager supports two offline or boot-time defragmentation modes. The first mode automatically defragments critical system files (i.e., paging and registry files). A second mode—Advanced Mode—uses a Windows Preinstallation Environment (PE) bootable CD that incorporates Windows kernel-mode technology to perform a complete system defragmentation, including data files, file-system metadata, and other files that might be untouchable when Windows is running. Using Advanced Mode, you can defragment volumes that are formatted with a cluster size larger than 4KB. For greater efficiency, this mode can also use space allocated to a paging file on the volume. Even in its offline modes, Defrag Manager is fully compliant with Windows file system APIs.

Management features. As its name implies, Defrag Manager is designed to help you implement and manage the defragmentation of systems across your enterprise. Defrag Manager doesn't include a client-side GUI interface to support users' control of system defragmentation, although you have the option to permit users to pause and resume defragmentation from a system tray icon. You can also run Defrag Manager from the command line, so you can create defragmentation scripts on licensed systems.

You install Defrag Manager on the computer that you'll use to manage and monitor defragmentation of systems throughout your network; this computer becomes the Schedule Console. Defrag Manager has deployment and management modes for systems with File and Printer Sharing enabled, for those without File and Printer Sharing enabled, and for portable systems through a third Disconnected Computer mode. After creating a defrag schedule to describe when and how Defrag Manager will defrag a system, you assign computers or groups of computers to the schedule. OU Binding lets you assign an AD OU to a schedule; then, Defrag Manager will automatically manage defragmentation for all computers in the OU. (This functionality includes license management; Defrag Manager assigns and frees licenses as OU membership changes.) Defrag Manager also supports a drag-and-drop method of assigning computers to a schedule. Figure 3 shows Defrag Manager's Schedule Console.

Aside from its Preinstalled Agent mode, Defrag Manager runs as a scheduled task, not as a service, both on clients (in Disconnected Computer mode) and on the Schedule Console. From the Schedule Console's GUI, you can also request an immediate analysis or defragmentation of a client volume—except, of course, for clients in Disconnected Computer mode.

Defrag Manager offers compelling reporting features. From the Schedule Console, you can view a nicely formatted report of the most recent action to occur on a computer, as well as the most recent log files detailing scheduled defrag actions for a computer.

Testing. Defrag Manager performed the most complete file defragmentation of the products reviewed here (by a hair), leaving no file fragments in either of my tests. With limited (5 percent) free space, it ran longer—by 38 minutes—than any other product. See Table 1 for the comprehensive results.

Defrag Manager is effective and easy to implement. It doesn't give users much control over the defragmentation of their own systems, but in most cases, that's not such a bad thing. I particularly valued the simplicity of the product's design. With only one version of the program for all supported systems, management by OU, and its use of Scheduled Tasks, Defrag Manager is a lean, mean defrag machine.

Bottom Line
Each of the programs I've reviewed accomplishes defrag's fundamental job: maintaining system performance in the face of volume fragmentation. Table 2 summarizes the products' differences in features, but the greater differences show up in the way the individual products implement these features.

Diskeeper offers an extremely workable package. Its Set-It-and-Forget-It scheduling and I/O-sensitive throttling of defrag activity in the presence of other system activity is perfect for routine workstation volume maintenance. I found its management console a little more complex and less intuitive than Defrag Manager's console. Diskeeper's product line is hands down the most complex of any of the products, with many versions and version-specific limitations. In spite of the fact that file defragmentation is much more important than free-space defragmentation, I find it puzzling that Diskeeper lacks a mode with which to aggressively consolidate free space on demand, because sometimes that's just what you want to do.

PerfectDisk has an efficient defrag engine with flexible scheduling options, but I didn't find the console particularly easy to use to manage groups of computers. Using the AD Administrative Template with Group Policy to configure and schedule defragmentation can help make up for that.

Defrag Manager excels thanks to its user friendly features—particularly, its simple deployment architecture, its intuitive console program, and its support for scheduling by AD OU or by groups that you define. The Advanced Mode Boot CD's ability to perform a complete offline defragmentation uniquely accommodates difficult situations. The CLI defrag program adds the extra flexibility you need. This combination of ease of use, simplicity of design, and broad capability make Defrag Manager my Editor's Choice.