VIO data set pages can be directed to a subset of the local paging data sets through directed VIO, which allows the installation to direct VIO activity away from selected local paging data sets that will be used only for non-VIO paging. With directed VIO, faster paging devices can be reserved for paging where good response time is important. The NONVIO system parameter, with the PAGE system parameter, allows the installation to define those local paging data sets that are not to be used for VIO, leaving the rest available for VIO activity. However, if space is depleted on the paging data sets made available for VIO paging, the non-VIO paging data sets will be used for VIO paging.

The installation uses the DVIO keyword to either activate or deactivate directed VIO.