Oracle Tips by Burleson

Oracle10g Grid Computing with RAC
Chapter 8 - RAC Administration

Thread Features

Figure 8.2 Redo Groups on a shared storage

Use a minimum of three or more redo groups in a thread. Keep at least two redo members for each redo group, for multiplexing and protection. Multiplexing the redo members is optional, but is highly recommended. Different degrees of mirroring are permitted in different threads.

The redo log thread can be public or private. When the redo thread is enabled, it can be specified as a ‘private’ thread. This means it is associated with a specific instance as defined in the initialization parameter thread of the instance. Alternatively, it can be specified as ‘public,’ in which case any instance can acquire it.

Redo Thread Maintenance

The redo log files specified in the create DATABASE command become thread 1. Additional threads are created using the ALTER DATABASE ADD LOGFILE command.

For example, to create a thread while creating the database (a manual process):