To understand why you must defragment your hard drives, it’s useful to know something about how a hard drive stores information. When you write a string of data onto a disk, Windows finds space on the disk that doesn’t already contain data. On a new drive, most of the disk is empty, so it’s easy to write a large file or other string of data in a blank area on the disk. But when you delete a file, the drive returns the space that the file had occupied to its “bank” of space available for new files.

However, the next file that you try to store might be bigger than the amount of space available in any single block. So the computer breaks the file into smaller pieces, called fragments, and stores each fragment in a different location on the disk. This is known as fragmentation. On a severely fragmented drive, a single file might be split into a dozen or more pieces. When the computer retrieves a fragmented file, it must reassemble the pieces before it can load the file into a program, so a fragmented file can take a lot longer to load than a file that’s all in one place on the drive. Keep in mind that Windows is constantly reading and writing temporary files and other data to the hard drive, so your computer will gradually become more and more fragmented, even if you don’t ever delete a permanent file. Over time, a drive that was zipping along when it was new will seem to take longer and longer to store and retrieve data, and your computer’s overall performance will become sluggish. Depending on the size of your drive and the amount of activity, you might not notice a difference for six months or more but it’s happening, and you should take steps to prevent it. A defragmenting program reassembles each file into a single block, and it creates the largest possible blocks of free space to allow room for new files without splitting them into fragments. Some more sophisticated defrag- menters also position the programs on the drives that are used most often close to the inside part of the disk. This allows the drive to find them more quickly than other files that you don’t use as often. Windows includes a perfectly adequate defragmentation program, but several other software vendors offer programs that do the same task more quickly or efficiently. If you have one of the general-purpose utility suites such as Norton System Works, you can use the defrag program included in that package instead of the Windows utility, but if you don’t have other soft- ware, the Windows program is good enough for most users. For a stand-alone defragmenter with an excellent graphic display, take a look at O&O Defrag from O&O Software (www.oo-software.com/en/products/oodefrag/). Diskeeper (www.diskeeper.com) is another well-regarded program.

Defragmenting a modern hard drive with a huge amount of space on it can take several hours or more, and it’s not practical to try to do any other work on the same computer while that operation is in progress. Instead, you might want to run the program overnight, or on a day when you don’t plan to use the computer for any other purpose. If another program adds or deletes data to the drive while a defrag- menter is running, the Windows defrag program might start over from the beginning of the drive. Therefore, a defragmenter running on an active drive can take forever to finish the process. You might come back after eight or ten hours and discover that only ten percent of the drive has been defrag- mented, just because the e-mail program has automatically checked for new mail every ten minutes. To eliminate this problem, turn off as many other programs as possible before you start the defragmenter use the CTRL-ALT- DELETE command to bring up the Windows Task Manager and shut down all the programs currently running in both foreground and background. If that doesn’t solve the problem, shut down Windows and restart in Safe Mode (press the F8 key while Windows reboots and follow the instructions on the screen), and then run the defragmenter program. To run the Windows defragmenter, follow these steps:

1. From the Windows desktop, open My Computer and right-click the drive you want to defragment.

2. Select Properties from the pop-up menu, and choose the Tools tab. A dialog box will appear. In older versions of Windows, the dialog box will also tell you when each tool was last run.

3. Click the Defragment Now button. The Disk Defragmenter will start. If you have installed a third-party defragmenter such as Norton Speed Disk or Diskeeper, that program will run instead of the Microsoft utility.

4. Click the Analyze button. The program will examine your drive and display the current amount of fragmentation. If the disk is heavily frag- mented, the program will recommend that you run the Defragment program.

5. To defragment the disk, click the Defragment button. The program will analyze the drive again and then start to defragment the files. This proc- ess will take a long time to complete, so you will probably want to do something else for a few hours, or you can leave it to run overnight. If the defragmenter doesn’t seem to be making any progress, confirm that everything else is turned off and try again.

Check for Other Disk Problems

Fragmentation isn’t the only problem that can occur on a hard drive. If a few crucial data bits stored on the drive become corrupted, it may no longer be possible to find or retrieve an entire file. If some extremely crucial bits become corrupted, the whole drive could become impossible to read. These errors are caused when Windows shuts down without properly saving open files, but it’s also possible for disk errors to occur due to nonspecific bit rot. article 2 of this article includes instructions for recovering from some of these problems after they occur, but you can also take some steps to prevent them. Sometimes the drive’s file system might have an incorrect setting that instructs it to assign more than one filename to data in the same location. Of course, the data at that location belongs in only one file; the second assignment is a mistake called a cross-linked file error.

It’s also possible for data to exist on a drive, but not in the file system. If the data doesn’t have a filename assigned to it, the computer can’t read it without special tools. The portions of the drive that contain these orphans are known as lost clusters or lost fragments. Modern disk drives are a lot more reliable than the drives that were provided with computers ten or fifteen years ago, but they can still suffer from file system errors. So Windows includes a utility program called Scandisk that examines all the data on a drive and identifies cross-linked files and lost clusters. When the program detects these errors, it can either correct them automatically, or display a list of errors and wait for a separate command to fix them. Windows automatically runs Scandisk when you turn on the computer after an “improper” shutdown. You can also run it from within Windows by following these steps:

1. From the Windows desktop, double-click the My Computer shortcut to open Windows Explorer.

2. Right-click the icon for the drive you want to test. Choose Properties from the pop-up menu. The Drive Properties window will open.

3. Select the Tools tab in the Properties window. The System Drive Proper- ties dialog box will appear.

4. Click the Check Now button in the Error-checking section of the Tools dialog box. The program will offer some options.

5. The options include automatically fixing errors and scanning for bad sectors. These options appear slightly differently in different versions of Windows, but they have the same effect. Turn on the Automatic Fix option, but don’t bother scanning for bad sectors. Click the Start button to begin the scan.

6. A complete scan will take less than half an hour unless your drive is seriously corrupted. Don’t run any other programs while the scan is in progress. Unlike the defragmenter, which you can run and ignore until the job is complete, you should check the computer for error messages every few minutes.

When the Scandisk program finds an error, it will either flag the problem and bring it to your attention, or it will automatically fix it by deleting the cross-linked file or the lost cluster and creating a new text file that contains the data that had been in the deleted file or cluster. It’s a good idea to take a look at each of those files after the scan is complete to see if they contain anything you want to keep. The contents will most often be digital gibberish, which you should delete. If there’s a useful string of text in one of the salvaged files, copy it to a new text file using a text editor such as WordPad and assign a name that describes its contents.

Create a Set of Utility Disks

Normally, your computer uses the files on your system drive to start Windows, but when your system drive fails (or the Windows files become corrupted), you’ll have to use software from a CD, a floppy disk, or another source to start the computer. The time to make those disks is now, before you need them.

Make a Restore Disk

Whether you have a copy of Windows XP in the original Microsoft package or a restore CD that came with your computer, you can use the startup files on that CD to reinstall Windows. However, if your computer came with restore files in a folder or a hidden partition on the hard drive, you might have a serious problem if the drive breaks down. You must make your own restore disk before the hard drive fails. When you unpacked the computer, the instructions for assembling the system and starting Windows probably included a section about making restore disks: almost nobody pays any attention. By that time, your shiny new computer was up and running, and you were exploring all the exciting new bells and whistles that came with it. Now that you have had plenty of opportunity to ring the bells and blow the whistles, take the time to make your restore disks now. There’s probably a command in the Windows menu that will start the process: if you can’t find it, look for instructions in the startup guide and other manuals that came with your computer.

Make a Boot Disk

When the system drive won’t load Windows, even in Safe Mode, it’s often helpful to start the computer from a “boot disk” that loads a simple operating system. You can use this system to examine and evaluate the contents of your drives and possibly create copies of data files that you can use on another computer. If the computer has a floppy disk drive as well as a CD drive, you should make boot disks in both formats. To create a simple startup diskette (a floppy disk), follow these steps:

1. Insert a floppy disk in the diskette drive. 2. Open My Computer from the desktop, and right-click the floppy disk drive. It’s almost always the A: drive. 3. In the pop-up menu, click the Format command. When the Format window appears, check the Create An MS-DOS Startup Disk option. 4. Click the Start button.

If your computer does not have a floppy disk drive, you will need either a boot CD or similar software on some other media that your computer can read, such as a USB flash drive. Your best approach is to find a friend or a colleague whose computer still has a floppy drive (or try the public library), and copy the contents of a boot floppy to a CD. Windows XP does not provide an easy way to create a boot CD, so you’ll have to use a utility from another source: Datapol (www.datapol.de/dpe/freeware) offers a free program called NTFS4dos that provides full access to the files on an NTFS drive. The Bootdisk.com (www.bootdisk.com) website contains links to startup software for many Windows versions and for other operating systems. Free PC Tech offers links to several boot disks, but they’re all self- extracting files that write the software to a floppy disk. Go to http://freepctech.com/pc/002/files010.shtml and scroll down the page. After you download a program, run it on a computer with a floppy drive, and then copy the contents of the floppy to a CD.

Scan for Viruses and Spyware

As article 13 discussed, every computer user must take steps to keep viruses, spyware, and other security threats out of their systems. It’s an unfortunate fact that every computer that connects to the Internet will almost certainly become a target for viruses, spyware, and other forms of malevolent software. Security experts report that an unprotected computer will start to receive probes from unwanted intruders within a few minutes after it establishes an Internet link, so it’s absolutely essential to use effective tools to find and remove infections that have already installed themselves, and to keep additional nasties away from your system. In order to keep your computer clear of these potential problems, you must use these tools:

A firewall to keep unwanted programs and other intruders from gaining access to your computer. An antivirus program to inspect incoming e-mail, check file downloads, and block viruses that can destroy data files and consume memory and storage space. An antispyware program to detect and block programs that can hijack e-mail clients, web browsers, and other Internet services. All of the security patches and service packs released by Microsoft and other software vendors that apply to the programs installed on your computer.

If you don’t already have a firewall, an antivirus program, and an antispyware program installed on your computer, do it now. Make sure the automatic update features are active.

Get Rid of the Dust

One more form of preventive maintenance is often overlooked. Over time, most computers are likely to accumulate dust and other crud inside the case. Unlike the dust bunnies under your sofa, the ones inside the computer are more than just an aesthetic disaster. Excess heat is a common cause of damage to the CPU and other electronic components inside computers. The parts that produce the most heat usually have fans or other cooling devices attached to them, and the ventilation holes and fan in the case pull the hot air out and cooler outside air in. But if a blanket of accumulated dust insulates the components from the moving air, the heat might not have a way to escape. Therefore, keeping the inside of your computer clean can also extend its life. The same intake and exhaust fans that are supposed to move a stream of air through the computer case can also pull airborne dust into the machine, so dust collects on most internal parts whenever the computer is turned on. And if you have a cat or a dog, there’s probably a lot of their hair inside the computer, too. In particular, these parts will run cooler and better when they’re clean:

The motherboard The heat sink and the fan on top of the CPU The video or graphics adapter The memory modules The fans in the case, the power supply, and any plug-in cards mounted on the motherboard The hard drives

There’s no need to become a fanatic about dust inside the computer, but you should open it up and remove the dust several times each year. A small vacuum cleaner (or a larger one with a small hose) is the best tool for the job because it will provide a place for the dust to go, but a compressed air hose or a soft brush will also work. Be sure to turn off the computer before you start poking around inside, and don’t use a metal tool that could create short circuits or damage a fragile component. In addition to the obvious dust collectors on the motherboard and other electronic circuit boards, remember to clean the large flat surfaces on top of the hard drives and the sleeves and finger guards around all the fans. If your computer has a tower cabinet, dust has probably settled on the floor of the case, so you should clean that area as well as the internal compo- nents. If you’re using a desktop cabinet, blow a shot of compressed air into the space between the motherboard and the bottom of the case; reaching underneath the motherboard with a brush or a vacuum hose is not worth the trouble. Some computers, including many laptop models, have metal screens or mesh filters over the ventilation holes where the air enters the case. These screens can capture airborne dust before it gets into the computer, but as the dust collects on the screen, it reduces the amount of air that can flow through the screen and into the computer. This can allow the internal components to overheat. Use a vacuum, an air hose, or a soft brush to remove the dust from each screen or filter. A dirty monitor screen won’t break down any sooner than a clean one, but it’s harder to see the information on the screen through all the crud. If your monitor has a glass screen, use a household glass cleaner spray and a soft cloth to clean it; if it has a flat-panel screen, use a soft brush or a soft dry cloth. As I said at the start of this article, all of this maintenance is easy to ignore because it’s tedious and time-consuming, and it doesn’t provide any kind of instant gratification after you’ve done it. But it’s worth the time and trouble; losing the contents of your hard drive to a disk failure or other disaster can ruin your entire day. Indeed, if the information stored in your computer is important enough, losing it could destroy your business.