DB2 10.5 for Linux, UNIX, and Windows
DB2 10.5 for Linux, UNIX, and Windows
This parameter controls the initial size of the cluster caching facility (CF) connection pool.
When you set the cf_num_conns parameter to AUTOMATIC (the default), the DB2 database manager creates an initial number of CF connections for each member with each CF at start time. This initial number is based on the number of worker threads, (See: cf_num_workers - Number of worker threads configuration parameter), number of connections per worker thread, and the number of members in the cluster. The actual maximum value for the cf_num_conns parameter is calculated automatically by DB2 at member startup, based on those parameters.
If the cf_num_conns parameter is set to AUTOMATIC and then raised to a value higher than the current value, with an instance attachment, new CF connections are created. However, if you set the cf_num_conns parameter to a value lower than the current value, CF connections are not closed.
When the cf_num_conns parameter is set to AUTOMATIC, any dropped connections caused by a port failure (or other network problem) are reestablished evenly on the remaining ports. When a failed port comes back online, connections are rebalanced as required.
When you set the cf_num_conns parameter to a fixed numeric value, the DB2 database manager creates exactly that number of CF connections for each member with each CF at start time. There is no automatic growing or shrinking done by DB2 database manager.
If the cf_num_conns parameter is set to a fixed value, and then the value is increased or decreased, with an instance attachment, then the number of CF connections is increased or decreased immediately, according to the new value.
When the cf_num_conns parameter is set to a fixed value, a port failure does not increase the number of connections on the remaining ports. The number of connections made to each port remains at the number found by dividing the cf_num_conns parameter by the number of ports. That number does not change, even if some ports are offline.