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. 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.
Indexed directories are the set of all directories in the indexed virtual roots.
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. 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 .