The Cluster Edition requires more memory than a standalone SMP Adaptive Server. The additional memory supports internode messaging and cluster locking.
You can configure the memory for internode messaging using the CIPC regular message pool size configuration parameter. The default value is 8MB.
To support distributed cache coherency, the Cluster Edition automatically configures locks for buffer caches and system descriptors when an instance starts.
Each buffer in the data cache is automatically configured with a physical lock. The overhead for each physical lock is approximately 24.6% for databases with 2KB pages and 12.3% for databases with 4KB pages. Thus, for a 100M data cache, the additional memory overhead for physical locking is 24MB for 2KB pages and 12MB for 4KB pages.
The overhead for system descriptors averages about 1.5KB per open object. For best performance, the lock hashtable size parameter is automatically tuned to 8 locks per bucket. For a large cache configuration, lock hashtable size may be automatically tuned to several megabytes.
