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64 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.