June 1999

The System File Checker Protects Your Most Valuable Files

In this article, we'll demonstrate how to use the System File Checker to locate and repair missing and corrupt files. We'll also show you how you can take things one step further by using the System File Checker to protect your most important files.

System File Checker functionality

You'll find the System File Checker (SFC) tool by clicking Start | Programs | Accessories | System Tools | System Information. Once the Microsoft System Information tool opens, select System File Checker from the Tools menu to open the System File Checker dialog box, as shown in Figure A. By default, the SFC searches only for system files that have been corrupted. However, you can customize the settings so that the SFC also searches for changed or deleted files. We'll show you how a little later in the article.

Figure A: The System File Checker not only searches for corrupt system files, but also lets you extract original files from the Windows 98 CD-ROM.

Searching for corrupt system files

When you first launch the SFC, you're given the option to either Scan For Altered Files or Extract One File From Installation Disk, as Figure A shows. If you know which file needs to be replaced, you can begin the file extraction. However, it's most likely that you're not going to know whether or not you have any corrupt system files, so you'll need to begin the scan. You can do so by clicking the Start button.

Once the scan begins, the SFC uses a data verification file called Default.sfc that's stored in the C:\Windows directory to determine whether or not a system file is corrupt. The information that's in the Default.sfc file is written to the file from your Windows 98 installation source during setup. This information consists of the date, time, size, and version of each system file, as well as a checksum that can be read to determine the file's integrity.

Depending upon the number of files and folders it has to check, the SFC could take several minutes to complete the scan. As the scan processes, a Checking Files progress bar is displayed. As Figure B shows, when the SFC finds a file that may be corrupt, it offers you three different options: Update Verification Information, Restore File, and Ignore. If you know why a change has occurred to the file--perhaps you've installed a new application--you can select the Update Verification Information option to record the change in the Default.sfc file. Or, if you're unsure whether or not the file is truly corrupt, you can select the Ignore option to skip the file. Then, if you begin to experience system problems, you can run the SFC once more and scan for the corrupt file.

Figure B: If the System File Checker locates a corrupt file it offers you three options for handling the file.

Restoring corrupt files

On the other hand, if you don't want to take chances and are pretty sure that the file is corrupt, select the Restore File option to replace the file with the original one from the Windows 98 CD-ROM. When you select this option and click OK, the Restore File dialog box, shown in Figure C, allows you to specify where you want to restore from and where you want to restore to. The SFC automatically places the original location of the corrupt file in the Save File In text box, so just click OK and you're good to go.

Figure C: You can replace the corrupt file by restoring the original file from the CD-ROM.

If, for some reason, you need to go back to the existing file, have no fear--by default the System File Checker gives you the option to back up the file before performing the restore. If you don't want to be prompted to back up the file every time you execute a restore, you can turn off this option by modifying the System File Checker Settings.

To find out how to modify the settings refer to the "Customizing your settings" section of this article. In the meantime, to continue without backing up, just click the Skip button. The original file is then extracted from the Windows 98 CD-ROM and restored to the correct location on your hard disk. As soon as the file is restored, the SFC runs through the scan once more to check for any more corrupt files. When the Finished dialog box appears, click the Details button to view the System File Checker Results dialog box, as shown in Figure D. As you can see, the file was successfully restored.

Figure D: When the process is complete, you can view the results of the scan.

Customizing your settings

By adjusting some of its default settings, you can customize the SFC for your own particular work environment. To do so, launch the SFC and click the Settings button. The Settings sheet, shown in Figure E, is where you set the backup options that we discussed earlier. You can also specify whether or not you want the SFC to scan for changed or deleted files by selecting the corresponding check boxes.

Figure E: You can have the System File Checker also scan for changed or deleted files.

Now, if you click the Search Criteria tab, you can designate which folders you want included in the scan, and also which file types. Click the Advanced tab and you'll see that you can even create your own verification data file with custom search settings. If you combine the options on both the Search Criteria and Advanced tabs, the System File Checker becomes a powerful tool.

Imagine the possibilities

If given the opportunity, the System File Checker can become a quick and easy way to protect your most important documents. For example, suppose that you've created some important templates that you use on a regular basis. It's common for frequently used files to become corrupt or accidentally deleted--leaving you with the unpleasant chore of re-creating them. You can prevent this from happening by creating a new data verification file that scans for changes on your important files and templates. To begin, just copy all the files that you want to monitor and paste them to a folder that only you have access to. These will be the files that are used if you need to do a restore.

Next, you can either add the files to the search criteria for the Default verification file, or create a new verification file with special search criteria. We'll show you how to do the latter. First, click the Advanced tab and then click the Create button, shown in Figure F, to open the Create System File Checker dialog box. Select a location for your new SFC file and then type a name, such as Templates, in the File Name text box. Click Save to create the file.

Figure F: You can create your own verification data file with custom search settings.

Now, you need to add the list of files that you want to monitor to the search criteria. When you click the Search Criteria tab, you'll see that both list boxes are empty. To add folders to the Select The Folders You Want To Check list box, click the Add Folder button and locate the folder(s) where your files are stored. If there are subfolders that you want to check, make sure you click the Include Subfolders button, as well. Next, click the Add Type button to enter the file types you want to check. Using the Add File Type dialog box, you can enter either a file type extension, or a complete filename. If files will be added to the folder down the road, we recommend entering just the extension so you don't have to constantly monitor the search criteria for your Templates.sfc file. The Search Criteria sheet should now look similar to the one shown in Figure G.

Figure G: Add the folders and file types to your Templates.sfc search criteria.

Finally, your last step is to make sure that the Settings tab has both the Check For Changed Files and Check For Deleted Files check boxes selected. Then, just click OK to save your new settings and close the System File Checker Settings dialog box. Now, to monitor your important files, all you need to do is launch System File Checker, click the Settings button, and select the Advanced tab to choose your Templates.sfc file from the File Name dropdown list box. Then, just follow the procedures we outlined to verify the integrity of your important files.

Conclusion

The Windows 98 operating system includes many useful file and disk maintenance utilities that can lengthen the life of your PC. The System File Checker tool is designed specifically for verifying and restoring the integrity of your system files. In this article, we showed you how to configure and use the System File Checker for this purpose, as well as for protecting the integrity of your most important documents.

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