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DB2 Manager User Guide 73
StorageTek Proprietary
In the DB2 Manager environment, lack of available tape drives will cause the
DB2 Manager control region to enter allocation recovery. Issuing a reply of
WAIT will now mean that the application issuing the SQL command which
caused the tape allocation request will have to wait indefinitely for another job
on the system to release a drive, before continuing.
In this case, the end-user response time would be unpredictable. For this
reason, it is recommended that a reply of 'CANCEL' be made to the IEF238D
message. This will be interpreted by DB2 Manager as a 'drive unavailable'
condition, and the retrieval request will be rejected with a ‘resource
unavailable’ condition or optionally queued internally (if a non-zero value has
been specified for the TAPEWAIT parameter in the TAPECNTL parameter
library member). In this latter case DB2 Manager will retry the request until a
tape drive becomes available or until the TAPEWAIT interval is exceeded. .
It is recommended that the reply of 'CANCEL' be performed by an automated
operator reply facility, if present on the system, rather than via manual
operator entry. In this way, there will be no delay between DB2 Manager
receiving the retrieval request, and the rejection of the request with a
‘resource unavailable’ condition. This will minimize delays to users in
receiving notification of the unavailability of resources in performing the
object access.
Shutdown processing
As an immediate shutdown does not allow outstanding migrated row storage
and retrieval requests to complete, whenever possible the DB2 Manager
control region should be shutdown normally (ie) use the SHUTDOWN
operator command without the IMMED parameter.
In this context, it is recommended that operators issue a summary status
display command before issuing the DB2 Manager shutdown request.
If there are any outstanding requests identified by the summary status
display, these should be allowed to complete before issuing a normal DB2
Manager shutdown request. If necessary, an immediate shutdown request
may be issued in order to abnormally terminate outstanding requests, and
perform DB2 Manager shutdown processing.
Additionally, if the scheduler lock, as displayed from the summary status
request, is constantly unavailable (ie. permanent LOCKED status), then an
immediate shutdown should be issued, as a normal shutdown attempts to
acquire this lock before proceeding. This situation, if it occurs, indicates an
internal DB2 Manager error condition, and should be communicated to your
DB2 Manager product support representative.
In extreme cases, the DB2 Manager control region may be cancelled if
required. Canceling the control region has the following consequences:
• Any outstanding requests will be left unsatisfied in a wait state (ie) control
will never be returned to the calling application. These applications will
have to be abnormally terminated by an external source.