CDDS_MODE in macro DSN6LOGP
The CDDS_MODE subsystem parameter specifies how Db2 uses a compression dictionary data set. In a GDPS® Continuous Availability with zero data loss environment, CDDS_MODE specifies how a member of a Db2 data sharing group participates in that environment.
| Acceptable values: |  NONE, SOURCE, PROXY, SOURCE_ONLY |
|---|---|
| Default: | NONE |
| Data sharing scope: | A setting of SOURCE or PROXY is valid only in a data sharing environment. All members of a data sharing group must have the same setting. |
| Online changeable: | No |
| DSNZPxxx: | DSN6LOGP.CDDS_MODE |
- NONE
- The Db2 subsystem or data sharing group does not participate in a GDPS Continuous Availability with zero data loss environment. The subsystem or data sharing group member supports only replication of its own log. The data set that the CDDS_PREFIX parameter specifies can be defined locally but is not used.
- SOURCE
- The data sharing group that contains the member that is being installed is the source group in an implementation of the GDPS Continuous Availability with zero data loss solution. The source data sharing group supports replication of the logs and log data sets of its members by another data sharing group, which is the proxy group in the implementation of the GDPS Continuous Availability with zero data loss solution. The proxy group performs replication of tables in the source data sharing group that are enabled for changed data capture.
The source group must contain a key-sequenced data set with the name that is specified by the CDDS_PREFIX subsystem parameter. That data set is the compression dictionary data set (CDDS). When IFI READS calls are made to the proxy group to retrieve compressed log records, Db2 uses the CDDS to decompress the log records.
The location of the source group must be defined in the communications database of the proxy group.
- PROXY
- The data sharing group that contains the member that is being installed supports only replication of log data sets for the source data sharing group in an implementation of the GDPS Continuous Availability with zero data loss solution.
The location of the proxy group must be defined in the communications database of the source group.
- SOURCE_ONLY
- The stand-alone Db2 subsystem that is being installed or the data sharing group that contains the member that is being installed uses the expansion dictionary that is stored in the CDDS to decompress log records. The Db2 subsystem or data sharing group must contain a key-sequenced data set with the name that is specified by the CDDS_PREFIX subsystem parameter. That data set is the compression dictionary data set (CDDS). When IFI READS calls are made to retrieve compressed log records, Db2 can use the CDDS to decompress the log records. In a data sharing environment, the SOURCE_ONLY value is valid only if the data sharing group does not participate in an implementation of the GDPS Continuous Availability with zero data loss solution.