DFSMSrmm performs validity checking on volumes when you read or write to them if DFSMSrmm is recording information about the data sets on the volumes. If you are running DFSMSrmm in protect mode the volume is rejected under these conditions:

• The wrong volume is mounted for a specific volume request.
• An attempt is made to use a specific scratch volume. In DFSMSrmm, when you want a specific volume, you must request a specific, non-scratch volume, and when you want a scratch volume, you must request a non-specific mount.
• A private volume (master or user) is mounted in response to a scratch request.
• The data set information for the first file on the volume that DFSMSrmm has recorded during open, close, or end-of-volume processing does not match the information on the volume.
• An attempt is made to overwrite a data set on a master volume and the specified data set name does not exactly match the data set name that DFSMSrmm has recorded. You can control the overwriting of data sets on master volumes using the EDGRMMxx OPTION MASTEROVERWRITE operand. If both the data set being written, and the data set DFSMSrmm has recorded are generation data group data sets, DFSMSrmm ignores the generation data group suffix when comparing the data set names.

  If the volume is part of a multivolume sequence containing multiple data sets, DFSMSrmm uses only the first volume, first file data set name for validation; for all other volumes the sequence of volumes is validated to prevent overwrite.

• An attempt is made to read a data set that DFSMSrmm has not recorded, and the volume information was previously recorded by DFSMSrmm.
• An attempt is made to automatically label a non-scratch volume in an automated tape library.
• An attempt is made to write on a volume that should be replaced (release action REPLACE).