Checking the next volume

When volume switching is performed, the EOV routine checks the volume and header labels on the new volume to ensure that the correct volume is mounted.

RACF access authorization is required for system-wide RACF tape protection. READ authorization is required if the volume is opened for INPUT or RDBACK. UPDATE authorization is required if the volume is opened for INOUT, OUTIN, or OUTINX. If a multivolume data set is RACF protected, then each volume data set must have the same profile for INOUT, OUTIN, or OUTINX (not INPUT or RDBACK) access.

No authorization is required if the new volume is not RACF protected and the user is authorized.

A specific volume request fails if the new volume is RACF protected and the user is unauthorized.

For a nonspecific volume request, the operator mounts a volume.

If the user is READ authorized but not UPDATE authorized, and the data set is open for INPUT or RDBACK, the system verifies that the volume is set to prevent writing. If the volume is not protected, the operator is notified to prevent the tape volume from writing by removing the write-enable ring from the reel or changing the write-protect tab on the cartridge. Protecting data describes when operator intervention is necessary, and when other mechanisms of protection eliminate the need for it.

The method of locating and checking the HDR1 label varies according to the situation. The processing depends on whether the data set is a continuation of a multivolume data set or is a concatenated data set. In either case, the user exit for security verification may be taken, as described in Open/EOV user exit for security verification.
  • Multivolume data set: The data set sequence number is irrelevant for the second and subsequent volumes of a multivolume data set. The EOV routine assumes that the data set continues at the beginning of the new volume. Therefore, the first header label group on the tape is checked. The HDR1 label is checked in the same manner as when the data set was opened on the first volume. Processing is abnormally terminated if:
    • The data set name is not the same
    • The volume is password protected, no previous volume in the data set was password protected, and the system operator or TSO user is not able to enter a correct password
    Note: For volumes residing in an IBM automated tape library, or manual tape library, password protection processing of the data tape set is bypassed. These tapes can be protected with RACF.
  • Concatenated data sets: The EOV routine handles concatenated data sets with like characteristics. Such data sets are not necessarily the first on the volume, so the EOV routine positions the tape according to the specified data set sequence number. This positioning is the same as for opening a data set. The HDR1 label is checked in the same manner as when the first data set was opened, including verification of the password if protection is indicated.
    Note: For volumes residing in an IBM automated tape library, or manual tape library, password protection processing of the data tape set is bypassed. These tapes can be protected with RACF.

The HDR2 label on each volume after the first volume within a multivolume data set is not processed. The data set characteristics that were established when the data set was opened apply to all subsequent volumes handled by the EOV routine.

The data set's block count is not accumulated from volume to volume. It is initialized and verified separately for each volume.

Parent topic: End-of-Data or end-of-volume on input