If you use ASM and plan to connect to an ASM instance to retrieve change data from ASM-managed Oracle redo logs, you must configure an ASM login user ID that has SYSDBA or SYSASM authority.
For Oracle 11.1.0.7 or later ASM environments, create an ASM user and grant one of the following authority levels to that user:
SYSDBA
SYSASM
To use SYSASM, you must also set the ASM_ASSYSASM parameter to Y in the READER statement of the PowerExchange Express CDC for Oracle configuration file, pwxorad.cfg.
For more information about creating an ASM user, see the