The data-set-changed indicator (DS1DSCHA) in the VTOC indicates whether or not the data set has changed since its last backup. Prior to z/OS V2R1, during full-volume restore, DFSMSdss unconditionally reset (turned off) the data-set-changed indicator for each data set restored to the target volume. During tracks-restore, if any VTOC track was restored, DFSMSdss unconditionally reset the data-set-changed indicator for all data sets on the volume.
With z/OS V2R1, a RESET keyword has been added to the RESTORE FULL and RESTORE TRACKS commands. It allows you to specify whether the data-set-changed indicator is to be reset for the data sets on the volume being restored. If you omit the RESET keyword on the RESTORE command, DFSMSdss resets the data-set-changed indicator only if the RESET keyword was specified on the DUMP command.
The RESET keyword on the DUMP command is not new. It specifies that the data-set-changed indicator in the VTOC is reset for all data sets that are serialized and dumped successfully. This applies to both a full dump and a data set dump operation.
For more information, refer to the topics about the RESTORE command and DUMP command in z/OS DFSMSdss Storage Administration.