The following options influence performance when using the index of a key-sequenced data set or variable-length RRDS. Each option improves performance, but some require that you provide additional virtual storage or auxiliary storage space. The options are:

• Specifying enough virtual storage to contain all index-set records (if you are using shared resources).
• Ensuring that the index control interval is large enough to contain the key of each control interval in the control area.
• Placing the index and the data set on separate volumes.