Configure the PowerExchange Express CDC for Oracle reader to connect to ASM instance to read the redo logs. PowerExchange establishes connections to both the ASM instance and Oracle database. The PowerExchange Express CDC log reader connects to the ASM instance based on the ASM_CONNECT_STRING, ASM_USERID, ASM_EPWD or ASM_PASSWORD, and ASM_ASSYSASM parameters that you specify in the READER statement. In the ASM_USERID parameter, specify a user ID that has SYSDBA authority or SYSASM authority. To use SYSASM authority, you must set the ASM_ASSYSASM parameter to Y in the READER statement in the PowerExchange Express CDC configuration file. Because of the required authority level, usually the ASM user ID is different from the following user IDs:

To improve CDC performance, you can run the Express CDC capture process and the PowerExchange Logger on the same node as the ASM instance. Alternatively, you can configure PowerExchange Express CDC to write chunks of redo log to a staging file on the ASM instance. The staging file can then be read by using standard I/O communication. For more information, see Using a Staging File to Optimize CDC Performance in an ASM Environment.

Use the interprocess communication (IPC) protocol for the PowerExchange Express CDC connection to the ASM instance. Ask your Oracle DBA to configure the Oracle listener.ora and tnsnames.ora files for IPC connectivity.