StorageTek 312564001 manual Display summary status

•Terminate the DB2 Manager control region.

All messages issued by DB2 Manager in response to an operator request are documented in chapter 7 of this manual. This section specifies operator request formats, and gives examples of DB2 Manager responses to these requests.

Display summary status

D(ISPLAY)

This request is used to produce a summary display of the status of the DB2 Manager control region processing configuration.

The DISPLAY command may be abbreviated to the single character 'D'.

DB2 Manager creates a number of tape and disk reader tasks in the control region to perform retrieval of objects from Archive Manager. Each tape reader task is capable of processing one tape volume at any one time. The number of tape reader tasks created is initially equal to the value of the MAXTRDR parameter at DB2 Manager initialization. Increasing this value during DB2 Manager operation will cause a similar increase in the number of tape reader tasks. DB2 Manager will only be able to process as many tape volumes simultaneously as there are initialized tape reader tasks.

Disk reader tasks may process multiple Archive Manager disk (‘K’) copy datasets in one invocation (ie. the task’s request queue may contain requests for retrieval of objects from different disk datasets). DB2 Manager attempts to balance the length of the request queues for the disk reader tasks. Increasing the value of MAXDRDR will reduce the average length of the disk reader task request queues. For most operational environments, the default MAXDRDR value of 4 will be sufficient. Note that the MAXQLEN parameter is not used to control a disk reader task request queue length; there is no limit to the number of requests which may be queued for each disk reader task.

If no disk reader tasks are available (MAXDRDR=0), a retrieval request for a disk-resident object will be passed to an DB2 Manager tape reader task, if one is available. This task will issue a standard Archive Manager object retrieval request, which will still be satisfied wherever possible by Archive Manager from an object’s disk copy. Setting the value of MAXDRDR to 0 in these circumstances is not recommended, as it may cause requests for retrieval of disk-resident objects to be rejected because there are no free tape reader tasks.

Writer tasks are capable of updating a single Archive Manager database at any one time. In addition, an Archive Manager database will not be updated by more than one writer task simultaneously. The number of writer tasks is controlled via the MAXTWTR initialization parameter.

A summary status request will display the current values of the MAXTRDR, MAXDRDR, MAXTWTR, MAXSCHED, MAXQLEN, RETAINTAPE, TAPEWAIT, OBJSIZE, READTIMEOUT and WRITETIMEOUT parameters,

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