Data Protection

CA 1 has the following data protection features:

For multi-data set tapes, each file is recorded and protected. Output is not allowed for any file other than n + 1 (where n is the number of existing files). The volume is retained based on the highest expiration date among all files on the volume.
For multivolume data sets, all volumes are chained, and updates affecting the data set (as opposed to the volume) can only be made to the first volume of the data set.
For multivolume data sets, an output volume cannot be remounted accidentally during multivolume data set creation.
On input, data set names are verified to help ensure that the data recorded in the TMC is correct for the volume. This also controls duplicate volume serial numbers.
On output, a tape cannot be written on unless it has been identified as a scratch by TMSCLEAN. Data set recreation on the same volume is permitted.
A permanent hold tape can never be written over. (DISP=MOD is allowed.)
The TMC is updated immediately at data set OPEN, CLOSE and EOV. There is no queuing of TMC updates.
MOD tapes are controlled so that:
- What is intended is allowed. Modifications are added to the data set.
- What is not intended is prevented. Modifications do not write over the current data set.
Nonlabel (NL) and Bypass Label Processing (BLP) tapes are controlled and protected.
The TMC is not updated if the tapes are not under CA 1 control that is, if they are non-CA 1 tapes.