To enhance IMS full function database facilities, High Availability Large Databases (HALDB) were introduced in IMS V7. As the name suggests, HALDBs are designed to increase the capacity and availability of DL/I databases. HALDB databases are implemented by dividing database records into sets of partitions that are treated as a single database, while permitting functions to be performed independently against individual partitions. Multiple partitions decrease the amount of data unavailable if a partition fails or is taken offline.
