How does DFSMSrmm validate tape mounts?

DFSMSrmm performs validation for all data sets on a volume that have been recorded by DFSMSrmm when a data set is opened. DFSMSrmm validates tape volumes as follows:

For specific tape requests, DFSMSrmm checks that the correct private volume is mounted.
For non-specific tape requests, DFSMSrmm checks that a scratch volume is mounted and that the volume is from an acceptable rack, scratch pool, or storage group.
For volumes where DFSMSrmm has recorded the first file creation at open time, DFSMSrmm checks that the last 17 characters of the data set name from the tape volume HDR1 label match the first file data set name known to DFSMSrmm.
For specific requests to overwrite data on a master volume, DFSMSrmm allows the overwriting of data based on criteria set by the EDGRMMxx OPTION MASTEROVERWRITE operand. DFSMSrmm checks that the data set name used matches the data set name that DFSMSrmm has recorded. For generation data group data (GDG) sets, DFSMSrmm removes the GDG suffix before checking the data set name.
At open time for the file being referenced, DFSMSrmm checks that the data set name used matches the one DFSMSrmm has recorded. If only the first file on a volume is being recorded, DFSMSrmm only validates the first file on the volume.
If DFSMShsm is reading a tape volume, only the last 17 characters of the data set name need to match the data set information in the tape header label.
For scratch tapes mounted in a fully functional automated tape library, that have incorrect or missing VOL1 labels, DFSMSrmm checks the external and internal volume serial numbers. DFSMSrmm ensures that both the external volume serial number and internal volume serial number, if one exists, are either defined as scratch to DFSMSrmm or are not defined to DFSMSrmm. If validation is successful, DFSMSrmm uses the external volume serial number (obtained by the vision system) to request the tape VOL1 label is created by OPEN processing.
DFSMSrmm ensures that the mounted volume has the correct WWID. DFSMSrmm obtains the WWID for a WORM tape from the tape drive when the volume is mounted and used or when you define the WORM tape to DFSMSrmm using the RMM TSO subcommands.
When DFSMSrmm has a Write Mount Count for a WORM media, DFSMSrmm ensures that the mounted volume write mount count matches the value recorded in the DFSMSrmm control data set.

DFSMSrmm performs tape mount validation based on the DFSMSrmm running mode set in the parmlib member EDGRMMxx with the OPTION command and OPMODE operand as shown in Table 1.

Table 1. How the DFSMSrmm running mode affects tape mount validation
DFSMSrmm Running Mode	Tape Validation
Manual	DFSMSrmm does not validate volume usage.
Record-only	DFSMSrmm does not validate volume usage.
Warning	DFSMSrmm validates tape volume usage and issues warnings if errors are encountered. DFSMSrmm does not reject volume usage.
Protect	DFSMSrmm validates tape volume usage and rejects volume usage under certain conditions.

Use warning mode as you perform testing during conversion from another tape management system. When you are running DFSMSrmm in warning mode, DFSMSrmm validates your tape volumes but does not prevent their use. See Defining system options: OPTION for information about setting options in the DFSMSrmm parmlib member.