Full Scan
Incremental Scan
Forcing a Scan from Administration Pages

The process of inventorying the virtual roots (and the physical directories pointed to by the virtual roots) to determine which documents should be indexed is called scanning. By default, all readable virtual roots are indexed. If some readable virtual roots should not be indexed, they can be configured by the administrator.

There are two basic types of scans:

Full Scan
Incremental Scan

There is no manual intervention needed for either of the scans, because Microsoft Index Server automatically detects what type of scan to do and does it without user intervention.

Full Scan

In a full scan, all the documents in the directories that are inventoried are added to the list of documents to be filtered. A full scan is performed the first time a directory is added to the list of indexed directories. A full scan is also performed as part of recovery if a serious error occurs.

Incremental Scan

In an incremental scan, only the documents that were modifed since the last time they were filtered are added to the list of documents to be filtered. On startup of Index Server, an incremental scan is performed on all the indexed directories. This allows Index Server to determine which files were modifed when it was not running.

During normal operation of Index Server, all changes to the documents in the indexed directories are automatically tracked if the indexed directories are on computers running Windows NT. Indexed directories are the set of all directories in the indexed virtual roots. Some file servers, such as Novell NetWare and Microsoft® Windows® 95 file server, do not support automatic change notification. When a virtual root points to a remote share that does not support automatic change notification, Index Server does periodic scans of that share. The frequency of these periodic scans is controlled by the registry setting ForcedNetPathScanInterval.

Sometimes an incremental scan is also performed if the system loses change notifications. This can happen if the update rate of documents is very high and the buffer used to get change notifications from Windows NT overflows.

Forcing a Scan from Administration Pages

An administrator can force either a full scan or an incremental scan on any of the indexed virtual roots by choosing the Force scan virtual roots option from the administration page. This will show the list of virtual roots. By default, no scan will be selected for any of the virtual roots. You can select the appropriate type of scan for the virtual root and click Submit.

You can force a full scan when a new filter DLL is installed or if you do not want to wait for the periodic scan on a remote virtual root. Queries will continue to return documents, but query speed may slow down during the scanning and filtering.

Note Forcing a full scan results in all the files in a scope to be refiltered and could take a long time.