Restart data set

IMS writes system checkpoint information to the restart data set (RDS). During each checkpoint, IMS creates or updates a checkpoint ID table; IMS uses this table during IMS restart to determine from which checkpoint to restart the system.

If, for any reason, the RDS is not available at restart, IMS can obtain the required checkpoint information from the log. However, using only the log could considerably lengthen the restart process.

Generally, you do not need to know the content of the RDS. IMS finds the information it needs in the RDS and uses it automatically during a restart.