How the System File Checker Baseline Is Determined (188186)

SUMMARY

System File Checker (SFC) verifies the integrity of system files. After scanning for altered files, it offers to restore damaged files. If a file is found to be damaged, SFC prompts you to restore the original file. SFC can also be configured to notify you of changed and deleted files.

You can use SFC to:

Scan system files for damaged, missing, or changed files.
Extract original Windows 98 system files.
Track changes to the system and identify altered files.

The SFC baseline file (Default.sfc) maintains the tool's settings and a profile of system files. The baseline contains the following information for each file:

Location
Source
Cyclical Redundancy Checksum (CRC)
Date/Time Stamp
Size
Version

MORE INFORMATION

The SFC baseline for the retail version of Windows 98 comes populated with Windows 98 file information. The baseline is backed up and selectively updated during Windows 98 Setup. Running SFC for the first time establishes a profile of the system.

Default Windows 98 File Information

The following files provide the SFC baseline with the default list of files copied by Windows 98 Setup:

Copy.inf
Copy1.inf
Copy2.inf

The following files provide SFC with the source for the copied files:

Layout.inf
Layout1.inf
Layout2.inf

Windows 98 Setup

Windows 98 Setup copies the Default.sfc file to Default.sf0. SFC updates the baseline for files such as Vmm32.vxd that have properties that can vary. SFC updates the baseline with changes to the properties for these files without noting the changes in its log file (Sfclog.txt). If a file is missing, it is removed from the baseline.

The Sfcsync.txt file is a list of files to silently update in the SFC baseline during Setup. Sfcsync.txt is limited to the following locations:

   Sfcsync.txt   Actual location
   -------------------------------------
   10            Windows
   11            Windows\System
   12            Windows\System\Iosubsys
   13            Windows\Command
   22            Windows\System\Vmm32

Create System Profile

The first time SFC runs, it creates a profile of the system. All of the changes to the baseline are noted in the Sfclog.txt log file, with the exception of missing files.

Missing files are silently removed from the baseline the first time SFC runs, even if you enable notification for missing files. Files that are removed after SFC runs for the first time are identified as missing the next time SFC runs. You are prompted to restore the file if SFC is configured to check for missing files.

Changed files are noted in the log file and you are notified if the setting is enabled. A file is identified as changed if its date and version information changes. Changed files are identified in the Sfclog.txt file as "Updated" unless you enabled notification for changed files and chose to restore the original file.

You are always notified of damaged files. A file is identified as damaged if its date and version match, but the CRC value does not match the baseline.

You are not notified of files that are added to the baseline. Files that are added to the baseline are noted in the log file as "Added."