This document does not refer to batch and ASM mode. For batch mode the location of the database is irrelevant. For ASM mode the only way of reading redo logs is through OCI connection to the database.
To make redo log parsing possible – OpenLogReplicator must be able to physically access redo log files. It is up to the user to make that possible. You can run OpenLogReplicator on the same host as the database or on an another host.
OpenLogReplicator running on database host
This is the easiest solution. But it is not recommended for production systems. For this scenario you can run OpenLogReplicator on the same host as the database. In this scenario you can use any mode of operation.
Please mind that OpenLogReplicator may be using extensively memory and CPU. Please make sure that there are enough resources for the database to work properly.
OpenLogReplicator running on another host
This is the recommended solution. For this scenario you must make sure that the redo log files are possible to read. This may be achieved by:
- mounting read only remote filesystem (for example using SSHFS),
- reading from SRDF copy,
- reading from standby database,
- reading just archived redo logs copied by batch file;
OpenLogReplicator by default would read online redo logs and process transactions as soon as they are committed and this information is written to redo log. But it can also read just archived redo logs – in this scenario transactions would be processed when log switch is performed and redo log is archived.