Virtual I/O for work data sets

Although VIO data sets can provide performance improvements in many applications, these work data sets are generally not as effective as disk work data sets for DFSORT.

DFSORT temporary work data sets allocated to virtual devices (VIO) can provide reduced elapsed time at the cost of increased CPU time for DFSORT applications. In general, this is not a good trade-off and VIO should not be used for DFSORT work data sets.

If work data sets are allocated to VIO, the VIO installation option tells DFSORT how to handle allocation to VIOs:

VIO=YES causes DFSORT to accept the use of VIOs for work data sets.
VIO=NO causes DFSORT to reallocate work data sets from virtual devices to real devices. Note that in order for re-allocation to be successful, a real device with the same device type as the virtual device must be available.

Re-allocation of VIO data sets (VIO=NO) is recommended over no re-allocation (VIO=YES). However, it is better to avoid using VIO work data sets in the first place, since re-allocation wastes time and resources.