DFSORT temporary data sets allocated to virtual devices (VIO) can provide significant elapsed time improvements. However, the trade-off for improving elapsed time using VIO is a serious CPU time degradation.

VIO is recommended for DFSORT input and output data sets only. While DFSORT can use VIO for work data sets, Hiperspace is the preferred method of using storage to eliminate I/O to work data sets on auxiliary storage.

In a DFSMS environment, data sets used by DFSORT might be allocated to virtual devices by the automatic class selection (ACS) routines, overriding the VIO installation option in some cases. System-managed storage explains how the ACS routines can be changed to avoid VIO allocation for DFSORT temporary data sets.