Diskeeper 10 User's Manual

Theory of Operation 57
Chapter 5
Theory of Operation
This chapter describes the Diskeeper design goals and how those goals were met.
Introduction
As described in the introduction of this manual, the term disk fragmentation means two things:
• a condition in which pieces of individual files on a disk are not contiguous, but rather are broken up and
scattered around the disk volume; and
• a condition in which the free space on a disk volume consists of little pieces of space here and there rather
than a few large free spaces.
The effects of excessive fragmentation are twofold as well:
• file access takes longer because a file must be collected in pieces here and there, requiring several disk
accesses instead of just one; and
• file creation takes longer because space for the file must be allocated in little pieces here and there instead
of just one contiguous allocation.
Before the introduction of Diskeeper, there was no method for completely correcting the problems of file and
free space fragmentation on Windows NT computers or in a mixed Windows network.
Design Goals
In designing Diskeeper for Windows, the following goals were established:
• The product must be completely safe to use.
• It must improve Windows system performance. It is not designed to make the disk look “pretty”—it is
designed to improve disk performance and, as a result, overall system performance.
• It should process live disks without interfering with user access to files.
• It should run without operator intervention.
• It must defragment all possible files and consolidate free space into the smallest possible number of large
spaces.
Diskeeper defragments files and free space on a disk, allowing access to the files on the disk at any time while
Diskeeper is running.
Safety
Diskeeper is designed with safety as the highest priority.
To ensure the safe movement of files on Windows NT, Windows 2000, Windows XP, and Windows Server
2003 systems, Diskeeper uses mechanisms built into the operating system that were developed and
implemented by Diskeeper Corporation (then known as Executive Software), and fully incorporated into
Windows NT, Windows 2000, Windows XP, and Windows Server 2003 by Microsoft. On Windows 98 and
Windows Me systems, Diskeeper uses similar mechanisms used by Microsoft and others.
By using these built-in mechanisms, Diskeeper maintains cache coherency, file security and permissions
information, and file content integrity no matter how fragmented the files on the disk are.