RAM requirements

When configuring instances of CDC Replication, the default values are used for memory allocation.

RAM

Each instance of CDC Replication requires memory for the Java™ Virtual Machine (JVM). By default, 1024 MB of RAM is assigned for each instance of CDC Replication.

Use the IBM® Data Replication configuration tool to configure the memory for each instance of CDC Replication.

Although CDC Replication memory requirements will fluctuate, you must work with your system administrator to ensure the allocated memory for each instance of the product is available at all times. This may involve deployment planning since other applications with memory requirements may be installed on the same server with CDC Replication. Using values other than the defaults or allocating more RAM than is physically available on your server should only be undertaken after considering the impacts on product performance.

CDC Replication source deployments may require additional RAM in the following scenarios:
  • You are replicating large LOB data types with your CDC Replication source deployment. These data types are sent to target while being retrieved from the source database. The target waits until all LOBs (for each record) are received before applying a row. LOBs are stored in memory as long as there is adequate RAM, otherwise they are written to disk on the target.
  • You are replicating "wide" tables with hundreds of columns.
  • You are performing large batch transactions in your source database rather than online transaction processing (OLTP).