CDB Performance Tuning Reference

Use this table to quickly ascertain which CDB properties you can adjust to tune performance.

Because the RBS model uses staging and replication technology, as well as using a differencing algorithm to determine what to synchronize to each device, the CDB is one of the most critical components for performance in terms of processing power, memory, and disk performance. The CDB must also be scaled vertically (on larger hardware) because it supports all of the nodes of the cluster.

Recommendations Generally Suitable for 64-bit Production Servers
Property	Function	Default	Production Recommendation
CDB thread count	Sets the maximum multiprogramming level of the database server. It limits the number of tasks (both user and system requests) that the database server can execute concurrently. If the database server receives an additional request while at this limit, the new request must wait until an executing task completes.	20	200
CDB initial cache size	Sets the initial memory reserved for caching database pages and other server information. The more cache memory that can be given the server, the better its performance.	24MB	8GB
CDB disk configuration	Isolate the data and log on distinct physical disks. Of the two files, the log receives the most activity. Use disk controllers and SAN infrastructure with write-ahead caching in addition to high-speed disk spindles or static memory disks. The same database must support all cluster members. The faster these database drives perform, the better the performance on the entire cluster.	1 disk	2 disks 10K RPM
Default (CDB) connection pool maximum size	Sets the maximum (JDBC) connection pool size for connecting to the CDB from each cluster member. In the example production configuration, each Unwired Server is allowed more connections than the number of threads set in the CDB thread configuration. This ratio helps to ensure that the CDB database server is the control point for limiting resource contention in the cluster. In a server configured with the CDB connection pool settings set to 0, the actual number of connections used will correspond to the number of Unwired Server threads in use. The number of internal connections in use at any one time per thread varies, although fewer than four is typical.	100	0 (unlimited)