StorageTek 312564001 manual Tapecntl: Maxdrdr

Use: The MAXTRDR parameter specifies the number of active tape-reader subtasks which are to be created in the DB2 Manager control region.

Notes: This parameter indirectly controls the maximum number of tape drives which may be concurrently allocated by the control region.

If TAPEWAIT=0 is specified, requests which cause this maximum to be exceeded will receive a “resource busy” condition from DB2 Manager - an SQL error code of –652 will be returned to the calling application and field SQLERRD(6) in the SQLCA will contain the hexadecimal value x’0A’.

Non-zero values of TAPEWAIT will cause requests which encounter this condition to be held internally for processing until a tape drive becomes available, or until the time limit specified in the TAPEWAIT parameter is exceeded, at which point a “resource busy” condition will be returned to the calling application, as above.

This setting may be varied during DB2 Manager operation via the 'SET MAXTRDR’ operator command.

If this parameter is omitted, a default value of MAXTRDR=4 will be used.

TAPECNTL: MAXDRDR

MAXDRDR = nnn

Requirement: Optional

Default: 4

Validation: nnn = 1-3 digit numeric value in range 1 - 255

Use: The MAXDRDR parameter specifies the number of active disk- reader subtasks which are to be created in the DB2 Manager control region. This is set during control region initialization, and may be varied thereafter using the ‘SET MAXDRDR’ operator command.

Notes: This parameter indirectly controls the maximum number of Archive Manager ‘K’ copy files which are to be simultaneously allocated by the DB2 Manager control region for retrieval of disk-resident objects from Archive Manager.

Requests for retrieval of an object from an Archive Manager ‘K’ copy file are added to the disk-reader subtask with the shortest queue length. Increasing the number of disk-reader subtasks will reduce the average queue length per subtask,

38	DB2 Manager User Guide
	StorageTek Proprietary