System state data is comprised of the following files:
Boot files, including the system files, and all files protected by Windows File Protection (WFP).
Active Directory (on a domain controller only).
Sysvol (on a domain controller only).
Certificate Services (on certification authority only).
Cluster database (on a cluster node only).
The registry.
Performance counter configuration information.
Component Services Class registration database.
https://msdn.microsoft.com/zh-cn/library/cc785306(v=ws.10).aspx
https://technet.microsoft.com/en-us/library/cc938537.aspx