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A computer has very few moving parts to wear down, break down or slow down. The obvious exception is the hard drive. It has many moving parts that must operate at near perfection to fetch and store data efficiently. This fact makes the hard drive the prime suspect when processes seem to be lagging. If the hard drive takes too long to provide the data a program needs, processing speed can quickly change from instant to "hurry up and wait" status.
So what do you do about it? Disk defragmentation has long been the go-to cure for a sluggish computer. Until recently, if you asked most computer geeks how to speed things up, they would tell you to try a "defrag" before just about anything else. Today's faster, larger and more efficient hard drives make defragmentation a less effective solution for slow computers. In most cases, however, a defrag remains a relatively simple way to boost your system's speed and efficiency.
In this article, we'll explore the defragmentation process to learn what it is, how it works and the potential benefits. We'll also explore advances in hard drive and operating system technologies and how they affect the defragmentation process.
Windows File Management: Losing the FAT
Basically, a hard drive consists of a spinning disk over which a read/write head is suspended on an arm. The file management system divides the disk into rings, and then divides each ring into allocation units (or clusters). The size of these units varies depending on the size of the drive. In most cases, the operating system will automatically determine the best cluster size. Program and data files are divided into allocation units before being written to, or read from, the disk.
When a specific file is needed, the head moves to the assigned ring and waits for the spinning motion to bring the required allocation units to it. If the allocation units for the file are stored in a contiguous section of a ring, things can progress quickly. However, if the file is spread over multiple locations, things can slow down considerably. In some cases, the pieces of a single file can be in thousands of locations on the disk. This situation is called fragmentation.
In the days of DOS, Microsoft created a file management system called FAT (File Allocation Table). By today's standards, FAT was pretty thin when it came to storage limits and capabilities. Early versions of FAT (FAT12 and FAT16) limited file size to 2 GB. Volumes could be no more than 4 GB and file names could contain no more than eight characters.
A later version, FAT 32, expanded the limits and provided additional capabilities. Volumes could be as large as 32 GB and files could extend to a whopping 4 GB. FAT 32 was the file management system of choice for Windows 95 and 98. As applications grew more complex and files grew in size, a more flexible system was an absolute must.
When Microsoft introduced Windows 2000, it also created a new file management system called NTFS (New Technology File System). All versions of Windows XP and Vista use the NTFS system. According to Microsoft, the maximum volume size for NTFS is 2 terabytes and individual files can be as large as the entire volume. In addition to working with larger files, NTFS includes many other improvements, such as more powerful file security, enhanced error recovery and a more efficient file storage structure, which makes searches faster.
The NTFS file management system is one reason disk defragmentation may not provide the improved processing speed it once did, but it also helps to keep the system from slowing down in the first place.
So what happens when a disk becomes fragmented? On the next page, we'll take a look.
Fragmentation: Your Ducks are No Longer in a Row
Disks become fragmented as files are written and deleted. Fragmentation tends to get worse over time. When you install programs on a new disk, the allocation units are written to a single, contiguous area. As you delete existing files and write new ones, free allocation units begin to appear all over the disk. Before you know it, pieces of the file for your new computer game are spread around like seeds in the wind, causing the drive head to dart all over the disk like a game of "Whack-a-Mole." Not only does this slow down the file transfer process, it also causes additional wear and tear on hard disk components, potentially shortening the life of the drive.
When you first load programs and copy data to your disk, the allocation units (in this case, ducks) are written one after another. All neat and tidy. Over time, however, writing, deleting and rewriting files to the disk leaves empty space in lots of places. The more deleting and rewriting the hard drive does, the more spread out the ducks get.
Fragmentation is unavoidable, although newer hard drives are designed to reduce its effects. The best way to avoid spreading allocation units all over the disk is to use a high capacity hard drive. If the amount of free space available remains high, files are more likely to be saved in contiguous areas of the disk. In most cases, a drive that is at less than 70 percent of its capacity will not benefit significantly from the defragmentation process. This is particularly true with newer, high-speed drives. These drives spin at a higher RPM and have faster read and write capabilities. Also, they often have larger buffers in which to combine file segments before sending a large file to the operating system.
Although technology and the lower cost of drive capacity have significantly reduced the amount and the effect of fragmentation, fragmentation still exists. Today's drives are larger, but so are today's files. Once you've loaded a disk with music, games, applications and even a couple of full-length movies, fragmentation can still be an issue.
Windows Defrag
The Windows XP defragmentation program provides a visual display of the reduction in fragmented files. Note that there are virtually no red lines in the bottom representation.
Defragmenting your hard drive is relatively simple, but can use significant system resources, so it's better to do it when the computer isn't in use. Every version of Windows has a built-in defragmentation utility. These programs are actually subsets of third-party applications, such as Executive Software's Diskeeper. The complete Diskeeper software package includes additional capabilities, such as scanning one drive while defragmenting another. For most users, however, the Windows utility has all of the functionality required to get the job done.
Using the Windows onboard defragmentation utility is simple.
See part 2 of this.
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Sherman Hand