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Windows 7’s Defrag Utility

Fragmentation is a normal process that occurs as you use your hard disk. You would think that the subject would be exhausted by now, but Windows 7 has made the topic worth revisiting. Before we discuss how Windows 7 handles defrag, a review of the process is worthwhile.

Data on a hard drive is organized into clusters and tracks. The cluster is the smallest amount of disk space that the operating system can work with, and therefore the smallest amount of space that can be allocated to a file. On a disk using the NTFS file system, a cluster occupies 4KB or 4096 bytes of space. You can think of a byte as a character on a typewriter, like the letter "D". One character equals one byte. So a cluster could be considered as the amount of space needed to store a document with up to 4096 characters or less. If you revise the document and the new document now takes up slightly more space, even only one additional character, the system will set aside an additional cluster for a total of 8192 bytes.

Revisions and deletions of files, combined with the addition of new data to the disk, contribute heavily to fragmentation. If a file won’t fit into a cluster, the system allocates another cluster to complete the storage which may not be located next to the first cluster. Files can be broken up into hundreds or even thousands of pieces scattered all over a disk drive. When the file is deleted, previously used clusters are now available, usually resulting in further fragmentation especially if the file being deleted is fragmented. This can become a big problem eventually because fragmentation makes your hard disk do so much extra work that you can experience a noticeable slow down in your computer operations.

In Windows 7, Disk Defragmenter is automatically configured to run on a specific schedule. In theory, no one ever has to think or do anything about defrag ever again. The operating system does everything for you in the background. This is a real boon for Windows users because the more time that goes by without defragging, the higher the probability that some inexplicable problem develops. Different pieces of a file end up being stored in different sections of the drive, and the read/write heads work harder to read and transfer data into memory. File access takes longer and longer, wear and tear increases, and performance suffers. It could be longer boot times, mysterious lock-ups, refusal to shut down, and in extreme cases the system won’t even start.

In addition to totally automating the process, Microsoft has redesigned the utility with new capabilities. Before Windows 7, Microsoft’s defrag utility worked to keep all the pieces of a file in one contiguous piece. Windows 7 has a new algorithm that analyses each piece of a file and calculates its size. If the section is larger than 64MB, it is left alone. The reason is that Microsoft’s programmers have determined that the performance hit the defrag utility takes from moving the fragment is far less than the performance hit taken by normal read/write operations. The benefit of leaving it alone far outweighs the benefit of moving it.

Leaving the fragment alone incurs no wear and tear on the disk read/write heads plus all the other physical components needed to make those operations happen. Moving very large fragments to other locations could involve moving literally hundreds of thousands of smaller file fragments to accommodate the process. This new method involves considerably less demand on system resources and may actually increase the life expectancy of the disk drive. In return for a not quite full defrag process, you get a disk drive that’s likely to last longer, and still get far superior performance than a system that is getting progressively more fragmented.

Windows 7 does more than defrag automatically. Its redesign allows you to monitor the progress of the defrag operation if you wish to run the utility manually. Additional new features make the Windows 7 defrag utility far more powerful than any previous version. Let’s take a closer look into Windows 7 defrag utility to see what it really does. There is a considerable difference between standard disk drive technology and solid state devices. If Windows 7 detects a solid state drive on your system, it automatically disables defrag for that drive. This will happen if the drive is connected internally or externally. Defragging a solid state device is not only unnecessary but could reduce the life expectancy of the drive.

Except for solid state devices, disk drives are relatively inexpensive. Therefore, multiple drive systems are quite common. Windows 7 can defrag multiple disks simultaneously in parallel. You no longer have to wait for one drive to finish defrag before starting defrag on another drive.

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