The portal comes with several operations that can only be accessed through the jobs with which they are associated. These special operations are referred to as agents.
The Audit Log Management Agent job archives old audit messages into files and deletes old audit files.
The Audit Log Management Agent job also archives and deletes audit files according to the schedule set in the Audit Manager utility.
The Bulk Subscriptions Agent job subscribes users in bulk to the communities and portlets you specify in the Bulk Add editor.
The Search Update Agent job makes sure the search collection is synchronized with the database. You can run multiple instances of this job at the same time.
The Search Update Agent job also repairs the search index according to the frequency set in the Search Service Manager utility.