The SARTCP function is used only to copy View tapes from one media type to the same media type, as in when something goes wrong with a primary tape and you can then create another primary tape from the duplex tape (and vice-versa).
When going from one media type to another, the SARPAC function needs to be used.
SARPAC and the View backup are the only utilities that create new tapes.
Otherwise, no non-View utilities should ever be used to copy View tapes, as they are proprietary in their format.
ven a CA tape product should never be used to copy View tapes.
When a report goes to a new tape, the TAPESEQ number is noted, as well as the position of the report on the tape, in the report's index record.
When a request is made to retrieve a report from tape, it uses the information as to what TAPESEQ and position are indicated in the index record, and then it goes to the catalog to have that tape mounted.
When reports are written to View tapes, there is a block identifier created, so that a report can be immediately located when being retrieved from tape.
Using anything other than View utilities loses the block identifier.
The loss of the block identifier is what causes the tape reading errors.
SARPAC establishes the block identifier.
It also writes out only active reports, and can fill a tape, if necessary, so use of SARPAC can save storage.
The database is updated when the writing of the report to the new tape is completed.
SARPAC and the View backup function similarly in that they update, or use, the SARINIT TAPESEQ value.
SARPAC and the View backup function similarly in that they update the report's index record with the TAPESEQ and location on the tape.
The TAPESEQ points to another index record, for the tape, which identifies the full DSN of the tape.
Using the DSN, View then goes to the catalog, to see what volume it needs to have mounted.