System value and environment variable rules

System values and environment variables are treated as pseudo object types by Db2® Mirror and controlled by the RCL just like any other replication‑eligible object.

System values

Rules can be added by specifying the system value name and the pseudo object type value *SYSVAL.

When the RCL is constructed for SYSBAS, a number of system rules are added to the RCL for system values. Some system values must never be replicated while others must always be replicated and remain the same on both nodes. The remaining system values are set to be replicated by default, but their replication status can be overridden by a user rule.

To see the list of system values that are excluded or included by system defined rules, click on the gray padlock in the upper right corner of the table to Show System Rules. Set the object type to *SYSVAL and choose a replication state of either include or exclude. The following figure shows system values that are never replicated.

Figure 1. Excluded system values in the RCL

By default, all system values not defined by a system rule are included in replication. However, a user rule can be added to the RCL to exclude an individual system value. When adding a rule for a system value in the Db2 Mirror GUI, specify QSYS for the library, *SYSVAL for the object type, and select the system value name from the drop down. The GUI shows you all the system values that can be changed, as shown here.

To see all the system values with rules in the RCL, you can query the QSYS2.REPLICATION_CRITERIA_INFO view.

SELECT OBJECT_NAME, INCLUSION_STATE FROM QSYS2.REPLICATION_CRITERIA_INFO 
  WHERE RULE_SOURCE = 'SYSTEM' AND OBJECT_TYPE = '*SYSVAL'
  ORDER BY INCLUSION_STATE, OBJECT_NAME;

Environment variables

Unlike system values, system-level environment variables are excluded from replication by default by a system rule and must be individually included for replication.

To include an environment variable in replication, add an include rule using QSYS as the library name, *ENVVAR as the object type, and specify the environment variable name as the object name. Existing system-level environment variables can be selected from the drop down menu for the object name field. If the environment variable being added does not exist, its name can be typed into the object name field as shown below. Environment variable names are case sensitive.

Figure 4. Add a new rule for a system-level environment variable