A directory service consists of both a directory storage system called the “directory store” and a mechanism that is used to locate and retrieve information from the system. The primary functions of the directory service are managed by the Directory System Agent (DSA), which is a process that runs on each domain controller (abbreviated as DC). Active Directory is the directory service that is included with Microsoft Windows. It stores objects that provide information about the real entities that exist in an organization’s network like printers, applications, databases, users etc. Active Directory is a part of the domain controller. It is associated with one or more domains. It stores information about users, specific groups of users like the Administrator, computers, applications, services, files, and distribution lists etc. Active Directory then makes this information available to the users and applications throughout the organization.
Active Directory is an important component of the Windows environment. Like any other Windows applications, its performance can affect the rest of the target environment. Active Directory consumes resources and the administrator needs to be aware of how much of the system's resources are being consumed over a long term. This helps the administrators to plan for future upgrades. Gathering performance data gives the administrators a good way to see the effects of any optimization efforts that he/she might attempt, and provides a great way for diagnosing problems when they occur