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Test Drive -
Diskeeper 5.0 (December 1999)
Eric Doyle test drives Diskeeper 5.0 from Executive Software

explorermag.com star rating

As an application progresses from version to version, it is often the case that additional functionality is replaced by tweaks to improve the efficiency of existing features and the addition of obscure features with minority appeal. Although Diskeeper has now reached version 5.0, its developer, Executive Software, is still adding features that will be gratefully received by the majority of its existing user base and should increase its appeal to new customers.Diskeeper 5.0 is supplied in separate packages. One is for Windows 95 (with OSR2), Windows 98 and NT workstations only and the other is for use on NT servers running Windows 4.0 with Service Pack 3 or higher or with Windows 2000. When used on Windows 95 or 98 some advanced features are not available, such as Boot-Time Defragmentation and Frag Guard.

All systems must have DCOM (Distributed Component Object Model) installed and networked systems must also have MMC (Microsoft Management Console). To avoid the need to check the records to see which systems have these options installed, the comprehensive but simple installation program will automatically detect their absence and install the services where necessary. The install routine also verifies which version of Windows is installed.

An additional boon to administrators is the remote installation feature which uses SMS (System Management Server). This requires a degree of manual setting-up of the SMS system but is preferable to visiting each server and workstation.

Once installed, there are three basic defragmentation modes: manual, the ‘Set It and Forget It’ scheduler, and Boot-Time.

Manual Defragmentation offers the greatest degree of control

Manual Defragmentation offers the greatest degree of control over the process but obviously makes the greatest demands on administrator time. Under manual control, individual volumes can be worked on and defragmentation can be interrupted and restarted at will. This is recommended when setting up the initial system because it offers the opportunity to use the Analyze function to give a detailed, colour-coded, graphical view of the volume, highlighting fragmented and non-fragmented files as well as specialised file types such as the MFT (Master File Table) in NTFS (NT File System) volumes and also shows MFT expansion areas; paging files in NT and Swap Disks for Windows 95 and 98; volume directories; and free space. After the analysis, a summary page is displayed to show the number of file fragments found and to offer advice on whether the volume needs defragmenting. It will also advise on whether the defragmentation process such be run more frequently.

After cancelling the verbal analysis, Diskeeper returns to the graphical display but before defragmentation, the administrator can save a text version of the report by clicking the View Report option in the Action menu. The report enumerates the degree of fragmentation of individual files as well as the basic volume details of size, cluster size, and free and used space. As the name suggests, the "Set It and Forget It" scheduler automates the defragmentation process. For standalone systems it can state when defragmentation should take place and when it should not. On the server version of Diskeeper this is supplemented by the Network Scheduler which allows a schedule to be created for all volumes or one or more networked computer, workgroup or domain.

Boot-Time Defragmentation

Boot-Time Defragmentation is only available on the NT server version. This executes operations that can only safely be done when the computer is powering up. It is a housekeeping process that consolidates parts of the file system that would normally be scattered across the disk. By moving all of the directories to the start of the disk and defragmenting the paging file and MFT, the system ensures that there is more contiguous space available on the disk for defragmenting normal files. Diskeeper will work without Boot-Time but using it optimises the performance. Dennis Crawford, systems engineer at Alston Drives and Controls, describes setting up Diskeeper as "an absolute doddle" but admits that it unavoidably takes some time. He explains, "It probably took ten minutes per machine to actually install the software but you then have to do a manual defragmentation, a Boot-Time and another manual defragmentation which adds another hour or maybe more depending on the size of the disk and how defragmented it is."

Up and running

There is little to say about Diskeeper when it is running on normal FAT (File Allocation Table) drives other than it does what it claims to do. It even works with hardware and software RAID and either stripe sets or mirror sets. When files are striped across a disk array, Diskeeper does not see the stripe as fragments of the same file but each disk stripe is treated as a separate file on a separate disk to ensure that data is never transferred from one disk to another. Mirror sets are handled similarly with each copy of the mirrored file being defragmented separately. Alan Galloway, technical support analyst for the Scottish Environment Protection Agency, said, "I’ve had no problems with Diskeeper. I just set it in the Set It and Forget It mode - and I’ve forgotten about it. Even the couple of RAID 5 systems we have seem to be working fine."

Diskeeper really shows its strengths in the NTFS environment which is much more complex challenge than FAT. In a white paper on The Effects of Disk Fragmentation on Windows NT 4.0 File System Performance, Executive Software concludes: "Comparison of the defragmented volume to the control volume does show, however, that even completely defragmenting files cannot fully restore the performance lost because of fragmentation. This is because of the fragmentation of the Master File Table… If allowed to continue so long that the Master File Table itself becomes fragmented, this can result in a volume that cannot be restored to full performance even with complete defragmentation."

Keeping in touch

This is why the Boot-Time Defragmentation option was developed but no one wants to schedule regular server re-boots just to keep the MFT under control – after all Windows tends to work out its own re-boot schedule with no intervention. To combat normal operational fragmentation of both the MFT and the paging file, Executive Software has developed Frag Guard which works on the fly to keep the files contiguous. Where the paging file is concerned, Frag Guard reserves a portion of the disk equal to the maximum size set up under Windows NT. Diskeeper makes this space available when additional paging space is needed. The module also monitors any MFTs on the disk volumes and attempts to keep them defragmented.

Frag Guard can also be set to initiate a Boot-Time defragmentation when either the MFT or paging file exceeds preset fragmentation limits. These limits can be individually set on the Frag Guard dialog box but the reboot process can be scheduled to only occur on a particular day or at a particular time. When a reboot is necessary, a user notification can be issued ahead of time to ask everyone to log-off. If anyone remains logged-on, the reboot is abandoned. The workstation version of this is a confirmation box which is displayed to warn the user of an impending shut down. The user can opt to reboot immediately or reject the request. If rejected or if neither option is selected, the reboot is aborted and rescheduled.

Frag Guard looks like it will be readily accepted with Crawford saying, "That’s the nicest thing in there. The fact that it will keep my disk defragmented without having to reboot so often is a great benefit."  Galloway is still testing the utility. He comments, "With one of the servers we’ve done a reboot to let Frag Guard kick in. It’s a great idea but only time will tell."

Peter Webb, head of technology development, Unilever Home and Personal Care, is less impressed. "Frag Guard seems to me to offer limited extra incremental benefit," he said. In normal operation, Diskeeper runs as a multitasking program which means that it can run happily in the background while normal computing tasks take place. It also means that several disks or disk partitions can be defragmented concurrently. To enhance the multitasking capability, there is a dialog box which allows the degree of priority given to Diskeeper to be set. On the highest settings it will noticeably affect other tasks running on the same machine, but at the lowest settings it will back off even if it is only the screen saver that is running.


Microsoft Windows NT Server Resource Guide suggests: "Disk fragmentation can cause performance problems. You should consider running a defragmentation program on a regular basis." To this end, Windows 2000 contains its own defragmentation tool but it will only defragment single volumes manually. This means the administrator would have to either visit every machine or grant administrative privileges to selected end-users. Diskeeper avoids both of these contingencies and Executive Software promises that if an upgrade is required when Windows 2000 is released it will also be available from launch.

Because defragmenters physically reorganise actual data, the big test is reliability. Peter Webb at Unilever HPC is a long-time user of Diskeeper. The product has been installed on Unilever’s 150 servers as part of the standard build for two or three years without major incident: "We did have initial compatibility problems with Dr Solomon’s Antivirus but Executive helped us sort that out. Over the last year or two we have had no significant problems." With Diskeeper 5.0 fresh on the market it is too early to pronounce that it has retained this reliability but its track record augurs well.

Diskeeper 5.0 is easy to install and does its job efficiently and effectively. The Frag Guard facility is a bonus to the system administrator because it maximises and prolongs the benefits of defragmentation, which means fewer reboots to reorganise the paging and MFT files. In addition, the "Set It and Forget It" network scheduling allows each workstation or server to be given its own settings remotely.

Why is defragmentation necessary?

A disk consists of an array of blocks in which the data is stored. An individual file is usually too large to be contained in a single block and the bigger the file the more blocks are used. Disk operating systems use algorithms that find the first free block and then attempt to store the rest of the file on consecutive blocks. On a new disk this is easily achieved but as time passes empty blocks appear all over the place due to normal disk activities, such as saving files, compressing files, deleting files, downloading e-mail, or installing applications. This means that the second block that a contiguous file would occupy is often in use by another and so the second block is found elsewhere on the disk and the file is stored in fragments scattered across the disk’s surface. When files are fragmented in this way, loading and saving files requires the disk head to skip and jump all over the place to access successive blocks. This not only means that disk accesses take longer than necessary but also increases the likelihood of disk read/write errors. Some errors may be self-corrected by the disk operating system, further slowing the disk operation, and some may not, resulting in incomplete file storage.

Defragmentation software cleans up the disk by restoring the files so that they occupy consecutive blocks thereby optimising access once again. This is achieved by locating the first block of a fragmented file, determining how many blocks this target file occupies, clearing the space required by moving data from successive blocks onto an empty part of the disk, and finally moving the target file data into the cleared area.

The data that is moved to create space for the target file cannot be discarded because it will be required data so the system notes what file owns that data and the blocks to which it has been moved. As the defragmentation process proceeds, these blocks will be moved back to slot in with their original owner when that file takes its turn as the defragmentation target.

Wish List

Although Diskeeper defragments paging file virtual memory, it would be helpful if it did something similar for virtual memory on the non-NT workstations. In the initial setup, automation of the Manual, Boot-Time, Manual defragmentation would be helpful but this may not be possible under Windows NT because of the need to reboot the system.

"I wish I could point to one of the fragments on the graphical display, right click it and have it tell me which file it belongs to." Dennis Crawford, Alston Drives and Controls


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