StorageTek 312564001 manual DB2 Manager User Guide, StorageTek Proprietary

If requested, DB2 Manager will create SMF records at the following points:

a.When all requests for retrieval of rows from a single tape cartridge volume have been completed by a tape reader task (ie) immediately before a busy task returns to wait status. The SMF record will contain one request section for each request processed during invocation of that reader task.

b.When the limit of 100 request sections has been created by a tape reader task while processing a request queue. An SMF record will be written by the reader task before continuing to process the request queue. One or more additional SMF records will subsequently be written by the reader task, either when the limit of 100 request sections has again been reached, or after all requests in the queue have been processed.

Note that there is no direct relationship between the number of requests that may be processed during a single invocation of a tape reader task, and the setting of the MAXQLEN parameter. After processing a request, the queue length will be reduced by one; however, new requests may continue to arrive and be added to the queue while the driver task is busy. New requests will only be rejected if the number of outstanding requests has reached the value of MAXQLEN.

In this way, there is no limit to the number of requests which may be processed during a single invocation of a reader task, and consequently no limit to the number of SMF records which may be written during that invocation.

c.When all queued requests for retrieval from the same Archive Manager database have been completed by a disk reader task (ie) immediately before a busy disk reader task processes a request for retrieval from a different Archive Manager database, or returns to wait status if there are no more requests in the queue.

d.During row migration processing, when the limit of 100 request sections has been created by a writer task. An SMF record will be written by the writer task before continuing with row migration processing. One or more additional SMF records will subsequently be written by the writer task, either when the limit of 100 request sections has again been reached, when a disconnect or commit request is received, or when the task has timed out waiting for receipt of another store request for the Archive Manager database being updated.

Each request section in an SMF record will contain four timestamps relating to the DB2 Manager retrieval request described by the record. These timestamps are issued at the following points:

1.When the request for access to a migrated row is intercepted by DB2 Manager.

2.Start of request processing by the control region scheduler.

3.Start of request processing by the reader or writer task in the control region.

64	DB2 Manager User Guide
	StorageTek Proprietary