How To ScanDisk
By: Source: AARP.org Date Posted: 2002-07-18 11:55:58
When you shut down your computer properly by clicking the Start button and choosing "Shut Down," your computer goes through a formal "shut down" process. During this exercise, files are closed, unnecessary files are deleted, and copies of important files such as the system registry files are written to the hard disk. A computer keeps track of the addresses of all files and clusters (pieces of files) in a table called the FAT table (File Allocation Table).
The Problem
If the power goes off, a program crashes, or you simply turn the computer off without going through the proper shut down procedure, the FAT table may be damaged. Files may become cross-linked, or clusters may be lost or orphaned. In essence, this means that their addresses have not been recorded properly. When this happens, it is essential that the computer be allowed to repair the files and their addresses before files are accessed during normal use.
The Remedy
Windows comes with ScanDisk, a slick little utility that can easily repair this type of damage. It is very important to run ScanDisk immediately after a computer crash or other improper shutdowns. In fact, running this utility is so important that in later versions of Windows 95 and all versions of Windows 98, ScanDisk runs automatically when the computer is restarted after an unauthorized shut down. If your computer starts up with a blue screen that says "ScanDisk is now checking Drive C for errors," it means that the computer was shut down improperly and Windows has automatically begun the ScanDisk operation. In most cases, the computer will do all of the work. All you have to do is wait until the process is complete, at which time the computer will proceed right to its normal boot up sequence. Don't be tempted to abort this process. It is important to let the computer complete the ScanDisk and repair any damaged files.
Problems like cross-linked files and lost clusters are "logical" problems in the computer's address keeping. A hard disk can also occasionally have physical problems. A physical hardware problem results from a disk's surface being scratched, contaminated, or demagnetized. A hard disk is divided into sectors; one or more of the physical sectors can be damaged by jarring, magnets, or contaminates such as cigarette ashes. A damaged sector on a hard disk can result in a multitude of computer problems. ScanDisk, however, is also capable of doing a surface scan to check for physical damage. If ScanDisk finds a damaged sector(s), it marks that area as unusable. Once the computer marks a sector(s) as bad, it will quarantine that area so that it will not cause any future problems.
Run ScanDisk Regularly
It is a good idea to initiate ScanDisk occasionally to keep your hard disk in tiptop shape. Start ScanDisk by clicking Start and choosing Programs, Accessories, System Tools, then ScanDisk. If you are using Windows 98, you have the option to schedule ScanDisk to run automatically at a specified time. Look under System Tools, choose Scheduled Tasks, and a wizard will walk you through the setup.
When you launch ScanDisk, it first asks which drive you want to scan. Normally, you'll scan only your hard drive although ScanDisk can be used on removable disks, as well. While you may want to scan a large removable disk such as a Jaz disk, don't bother scanning a floppy diskette. It is better to replace a diskette than to continue to use a damaged one.
ScanDisk can perform two types of tests: Standard which checks for cross-linked files and file fragments, and Thorough which adds a surface test for bad sectors. In the ScanDisk window, near the bottom of the screen is a check box to automatically fix errors. Unless you have some technical computer experience, you'll want to leave this box checked so the computer will perform its work automatically.
If you run a Thorough ScanDisk, the Advanced button at the bottom will let you customize the scan, control how ScanDisk repairs the errors, and create a log of the ScanDisk session. Again, in most cases, it's best to accept the default settings and let the computer make the decisions.
Close All Programs to Run ScanDisk
Running a Thorough ScanDisk can take a fair amount of time. Depending upon your processor speed and your drive's size, a full exam may take an hour or more. Though you can do other tasks while running ScanDisk, many of the programs that you use will need to read and write from the hard disk. When ScanDisk is running, each disk read or write causes ScanDisk to restart resulting in an even longer scan exercise. Screen savers can interfere with ScanDisk in this way, so you may want to disable your screen saver before running this utility. To turn off your screen saver, simply right-click anywhere on the Windows desktop and Choose Properties. Click on the Screen Saver tab. Then click on the arrow next to the words Screen Saver and choose None from the drop-down box.
Let the computer do its scan job when no other programs are running, if possible. As the scan progresses, a gauge across the bottom displays its progress. If the scan starts over repeatedly, you may have a program running in the background that is interfering with the ScanDisk's progress. If you feel this is the case, press CTRL+ALT+DEL at the same time and you will see a list of programs that are currently running on your computer. A program called FastFind is notorious for causing ScanDisk interference. If you see FastFind on the list, simply highlight it and press End Task. You can stop any or all programs that you feel may be interfering except the program called Explorer. This program is the Windows operating system. Keep it running or you will get a major error.
Keep Your Computer in Tiptop Shape
Average computer users should run a Thorough ScanDisk on a monthly basis. Be sure to let ScanDisk run automatically after any improper shut down. These practices will go a long way towards keeping your computer healthy and happy. It may keep you smiling as well!
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