If you have only one kind of tape device at your site, no consideration of tape device selection exists. For any tape-input or tape-output operation, only one kind of tape device can be selected.

However, if you have more than one kind of tape device at your site, a choice must be made as to which device is selected for a given function. You can direct MVS™ to select a device you specify, or you can allow MVS to choose the device for you. You can restrict MVS allocation to selecting the specific kind of tape device you want for a given function in either an SMS-managed tape library or in a nonlibrary environment. Restricting device selection can improve tape processing when high-performance devices are selected and can ensure that new devices are selected when they are introduced into your tape environment. For more information about restricting device selection, see Restricting tape device selection.