NDM (Nucleus Device Management) is the actual device management tool of BS2000. The basic function of device management is to allocate devices. Since, as a general rule, not every device request can be fulfilled, NDM must also offer a device reservation function, manage queues and process these queues.
NDM records the number and status of the devices at system startup time and changes in these statuses during operation.
If an application program issues a task to a particular device, if this device is available and if it is allocated by NDM, then NDM must also ensure that the device is flagged as occupied and no other application program has access to the device. This device remains occupied until the application program with access authorization has finished working with the device and has notified NDM.
Command | Meaning |
ADD-DEVICE-DEPOT | Defines assignment of tape device to depot |
CHANGE-DISK-MOUNT | Locks private disk for access |
CHANGE-TAPE-MOUNT | Changes mount status of tapes |
CHECK-DISK-MOUNT | Checks mount status of a disk |
CHECK-TAPE-MOUNT | Checks mount status of tape devices and MTCs |
MODIFY-MOUNT-PARAMETERS | Changes parameters for mounting and demounting tapes and disks |
MODIFY-RESOURCE-COLLECTION | Controls collector selection |
REMOVE-DEVICE-DEPOT | Cancels assignment of tape device to depot |
SECURE-RESOURCE-ALLOCATION | Requests resources |
SET-DISK-DEFAULTS | Defines default values for DISK parameters |
SET-DISK-PARAMETER | Sets defaults for monitoring disks |
SHOW-DEVICE-CONFIGURATION | Display the input/output configuration |
SHOW-DEVICE-DEPOT | Shows the assignment of tape device to depot |
SHOW-DEVICE-STATUS | Requests allocation and monitoring information for devices |
SHOW-DISK-STATUS | Shows assignment and DISK parameters |
SHOW-MOUNT-PARAMETER | Shows monitor defaults for disks and tapes |
SHOW-RESOURCE-ALLOCATION | Shows task allocation and open operator actions |
SHOW-RESOURCE-REQUESTS | Shows status of device queue and collector task |
SHOW-TAPE-STATUS | Shows tape allocation and monitoring |
START-RESOURCE-COLLECTION | Starts collector selection |
STOP-RESOURCE-COLLECTION | Terminates collector selection |
UNLOCK-DISK | Corrects system allocation log |
Macro | Meaning |
NKDINF | Information on the allocation and availability status of the (peripheral) configuration |
NKGTYPE | Information on the name, device type code, device attributes etc. of |
Table 12: Overview of interfaces for resource allocation and reservation
The NDM information services provide the operator with certain output fields appropriate to the specified command and the desired scope of information.
A list of the SHOW commands and an explanation of the information which is output are provided in the Appendix to the “Commands” manual [27].