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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.
Summary
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
Pricing
| Workstation |
£32.99 |
| Workstation 10pk |
£259.99 |
| Workstation 5pk |
£154.99 |
| Server |
£174.99 |
| Server 10pk |
£1,099.99 |
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