The tape library is released for BS2000 operation in two modes (library modes): Random Mode and Sequential Mode. ”Autoload” and “Loop” modes can also be activated in Sequential Mode. You can switch explicitly between Random and Sequential Mode, see "Device settings".
Random Mode
Random Mode is the default operation mode and also the normal operation mode when being used by BS2000. In Random Mode the application software controls when which cartridge is mounted or ejected.
When a manual action is initiated by the OCP (or RMU), e.g. the export of a cartridge (i.e. a cartridge is moved using the OCP menu Commands > Move Media, the tape library uses Sequential Mode for the duration of this action and then switches back to Random Mode. During this interruption of the current operation mode, the device displays “Busy Rand Action Move” in the operator control panel. Messages to this effect are displayed on the BS2000 console. Messages also report when Randos Mode is disabled or enabled.
Sequential Mode
From the BS2000 viewpoint Sequential Mode corresponds to automatic or manual mode with continuation tapes - all tapes are automatically used one after the other.
Sequential Mode has the additional options Autoload and Loop.
When Autoload is enabled and the drive is empty, the tape is loaded in the slot with the lowest number after the tape library has been rebooted or powered-on.
When Loop is enabled, following the last tape operation continues again with the first tape, otherwise the tape library will stop and wait for the user to intervene.