| Data set type | Description |
|---|---|
| State data set | The state data set contains status of the XRC session and of associated volumes that XRC is managing. The state data set is updated if an XADDPAIR, XDELPAIR, XSET, XSUSPEND, XRECOVER, or XEND command is issued, or whenever a volume state changes. If a session is coupled, the state data set identifies the master session it is coupled to, and is updated when an XCOUPLE command is issued. |
| Control data set | The control data set contains consistent
group information on the secondary volumes and the journal data set.
It contains information necessary for recovery operations. The control
data set acts as the table of contents for the session.
Example: The control data set keeps track of data written to secondary volumes, the location of unwritten data in the journal set, and which group to start recovery with. |
| Journal data set | The journal data set contains temporary user data that is created when records in the primary volume are changed or updated. |
| Master data set | The master data set ensures recoverable consistency among all XRC subsystems contained within the Coupled XRC system. |
| Cluster data set | The cluster data set is used to restart a cluster session. |
| Cluster state data set | The cluster state data set contains XRC monitor data for a cluster session. |