Managing the Replication Criteria List

Whenever an object is created, updated, deleted, or has its properties altered, Db2 Mirror uses the RCL to determine its replication status. Instead of maintaining the replication status as an object attribute, the RCL is used to determine if the operation needs to be replicated to the other node.

The RCL is a rules engine that consists of a set of hierarchical rules identifying either groups of objects or a specific object which should or should not be replicated. Rules are defined to either include or exclude objects from replication. These rules are used to determine the replication status of existing objects or newly created objects without requiring each object on a node to be individually cataloged within the RCL.

The RCL is assigned an initial rule called the default inclusion state during the Db2 Mirror setup process prior to the clone. The default inclusion state determines whether an object is replicated when no specific rule exists for that object. The default inclusion state is the highest level rule in the RCL and it has two possible settings:

• Exclude: No objects are replicated by default. To include specific objects as part of the replicated environment, additional rules must be created to identify the objects that are to be included.
• Include: All eligible objects are replicated by default. Additional rules can be created to exclude objects from replication.

Authority information, such as authorization lists and user profiles, and a subset of system values are always replicated.

The following figure shows the configuration screen on the Db2 Mirror GUI where the default inclusion state is set.

CALL QSYS2.SET_DEFAULT_INCLUSION_STATE(INCLUSION_STATE => 'EXCLUDE');

In addition to the rule defining the default inclusion state, Db2 Mirror primes the RCL with system rules. These rules are for objects that are always replicated for Db2 Mirror or for objects that can never be replicated by Db2 Mirror. These rules cannot be modified or overridden by a user rule.

The system administrator can add user rules to the RCL to define the replication status for replication-eligible objects. The scope of these rules is used to determine if a specific object is included or excluded from replication.

The scope of a rule refers to its hierarchical level within the RCL. These levels determine whether a rule governs all objects within a library, all objects of a specific object type within a library, or a specific object within a library.

The previous figure shows an example of the hierarchical structure of RCL rules. In this example, the default inclusion state of exclude is overridden to be include for libraries LIB1 and LIB2. Rules are defined to exclude all objects of type *FILE and *PGM in LIB1. Additional rules exclude all objects of type *FILE in LIB2 except for the file FILE4 which is set to include.