Recording technology
Cartridge cases have about the same physical dimensions, but the
physical tapes and the recording technologies differ. In the following
cases, the drive is not capable of reading existing data, but it can
read an existing volume serial number and the drive allows software
to write over the data with a different recording technology, for
example:
- 36-track tape mounted on a drive that is only capable of handling 18-track tapes
- 256-track tape mounted on a drive that is only capable of handling 128-track tapes
- EFMT2/EEFMT2-track tape mounted on a drive that is only capable of handling EFMT1-track tapes
Note: This
will only work between specific devices that support this functionality,
for example:
- between an 18 track device attempting to read the first block on media recorded on a 36 track device, or
- on a 128 track device attempting to read the first bock on media recorded on a 256 track device
- on an EFMT1 track device attempting to read the first block on media recorded on an EFMT2/EEFMT2 capable device
The OPEN or EOV functions rewrite the tape with the drive's recording
technology, possibly without standard labels, if all of the following
are true:
- The application program is opening to write to the first data set
- The volume serial number is available from the vol ID mark or from the external label from the vision system
- DFSMSrmm, the label anomaly installation exit routine, or the volume label editor installation exit routine allows the rewrite
- The user has RACF UPDATE authority to the volume or RACF is not controlling tape security
- The DEVSUPxx member of SYS1.PARMLIB specifies VOLSNS=YES