Here is an example of tasks involved in assigning installation-defined media information (StorageTek, in this case) to a volume:

1. Ensure that volumes can be displayed, updated by commands, read from and written to, and scratched. The following steps assume that you have a StorageTek library attached and that HSC/MVS is running. Both physical and virtual testing can be performed.
2. Next, code the MEDINF commands in the EDGRMMxx parmlib member. The external values used for media type and recording format must match those that HSC returns for volumes. Check that the values in the sample are what you want to use. If you wish to use different values, you can add additional entries to exploit the alias capability for external values. The first external value for each internal value is used for the LISTVOLUME command; all other values allow aliases either by the user or from the HSC or CSC PGMI. You might not want to use all the sample MEDINF commands, but a complete set of media types and recording format combinations is better than just having the minimum necessary for your installation. This ensures that the internal numeric values used can be converted in the future. Do not set a MEDINF(STK) for any volumes yet. Issue the Modify command to DFRMM started procedure to refresh the parmlib member to be the one you have updated. Repeat the testing from task 1 as necessary.
3. Now, set one or two volumes that you plan to use, but not all of the volumes, to have MEDINF(STK). You can use the RMM CV volser MEDINF(STK) command. The existing media type and recording format will display using the STK external values, rather than the IBM values. The resultant displayed information probably will not make sense to you, but should not cause problems.

   Select a volume and use the RMM CV volser MEDINF(STK) MEDIATYPE(stkvalue) RECORDINGFORMAT(stkvalue) command. The media type and recording format will now change for this volume. Once a volume has MEDINF STK, DFSMSrmm should no longer change the media type/format for this volume, unless the EDG_EXIT300 installation exit is in use, or you use additional DFSMSrmm commands to change this information.

4. If you are using the EDG_EXIT300 installation exit, this exit will work with HSC/MVS or CSC/MVS software and will try to record the correct values for your volumes.

Repeat these steps as necessary and, as the volumes are read or written, the correct media types and recording formats are recorded.

See Using the EDG_EXIT300 installation exit for information about the EDG_EXIT300 installation exit.