A tape device must be attached to a user process before it can be used. Use T-ATT to change the block size. The T-SELECT command attaches a device to a process, as well as specifying the logical tape unit. The T-ONLINE command makes the currently selected tape drive available to mvBase and attaches it to the process. If the tape drive is already attached to another process, the T-ONLINE command will fail.
The tape drive remains attached to the process until the user logs off, detaches the unit using the T-DET command, or attaches to a different tape drive. Once the tape drive is attached, the T-DUMP and T-LOAD commands can be used to write to tape and to read files from tape. Both are INFO/ACCESS commands.
Several commands serve the purpose of attaching the selected tape unit to your process., in addition to one or more other functions. The table below compares the application of these commands:
Command |
Description |
Application |
T-ATT |
Attaches the currently selected tape unit to your process. |
Use T-ATT to attach the tape drive if you want to change the block size. |
T-SELECT |
Changes the tape unit(s) from the default unit or the one(s) last selected, and attaches it to the current process. |
Use T-SELECT when you want to select another LTU than either the default unit or the last one selected, as well as attach the unit to the process. (See Selecting a Tape Drive for An Account for more information. |
T-ONLINE |
Resets the physical tape drive, checks that the tape has been inserted (or in the case of a VTF, that the destination directory/file already exists), attaches the tape drive, and rewinds the tape. |
Use T-ONLINE when you want to not only attach the unit to the process, but reset and rewind a physical tape, as well as checking to make sure the attaching procedure has been completed successfully. |
See Also