StorageTek 312564001 manual DB2 Manager User Guide, StorageTek Proprietary

The following control region components are illustrated in Figure 4:

•Control processor. This component is responsible for initiation and termination of the control region, and for processing operator requests.

•Writer tasks. There will be one or more writer tasks – the number of writer tasks is controlled via the MAXTWTR initialization parameter. A single writer task will be used exclusively for storage of migrated rows in an Archive Manager database, during execution of the DB2 Manager table migration utility. The existence of multiple writer tasks will enable multiple row migration jobstreams to be executed concurrently on different Archive Manager databases.

•Tape reader tasks. There will be one or more tape reader tasks – the number of these tasks is controlled by the MAXTRDR initialization parameter. A tape reader task will be invoked by the DB2 Manager SQL intercept processor during object retrieval, update and deletion processing, when a migrated row is to be retrieved from a tape- resident Archive Manager object. Each reader task will be able to process a single tape volume at any one time. The number of tape reader tasks controls the number of tape volumes which may be processed concurrently for this type of processing.

•Disk reader tasks. There will be one or more disk reader tasks – the number of these tasks is controlled by the MAXDRDR initialization parameter. A disk reader task will be invoked by the DB2 Manager SQL intercept during object retrieval, update and deletion processing, when a migrated row is to be retrieved from a disk-resident Archive Manager object. The number of disk reader tasks controls the number of disk retrieval requests which may be processed concurrently.

•Scheduler tasks. There will be one or more scheduler tasks – the number of these tasks is controlled by the MAXSCHED initialization parameter. A scheduler task is responsible for validating requests received from the DB2 Manager SQL intercept processor, and assigning the request to an appropriate reader or writer task. Increasing the number of scheduler tasks will reduce the length of time a request waits for validation and assignment processing, but will increase the processing overhead associated with the control region.

•Housekeeping task. A single housekeeping task will be initiated during control region initialization processing. It is responsible for monitoring outstanding requests, and terminating stalled requests.

DB2 Manager User Guide	47
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