This article was previously published under Q209304
In the Application log of the Event Viewer, events 4124 and/or 4126 may occur. The errors in the Event Viewer report that the catalog is corrupt. In the MMC snap-in for Index Server, the statistics for a certain catalog may contain a value of n/a instead of numbers.
Catalog corruption is most commonly caused by the following:
When you run a backup or virus scan against the Catalog.wci directory when Index Server is started. Because Index Server keeps many of the files in that directory open and mapped into memory, a backup can corrupt them as it may lock them in order to back them up. To work around this, either stop the Index Server (CISVC) or simply remove that directory from the list of directories you back up.
Anytime you restart a computer without shutting it down from the Start menu, you run the risk of corrupting files, and the Index Server catalog files are no exception.
If you edit the registry and set the FilterRetries key in the following location to a value below 4 (default is 4):
Often the trouble shooting of catalog corruption involves simply stopping and starting the Index Server. However, sometimes you will need to rebuild the catalog from scratch (stop Index Server, delete or move the contents of the Catalog.wci directory, and then restart Index).