Oracle Database Tips by Donald Burleson

Oracle10g Grid Computing with RAC
Chapter 15 - RAC Migration Topics

Conversion from Single-Instance to Cluster-Enabled System Administrative Concerns

Before beginning the conversion to RAC you should be aware of the following administrative considerations:

• Make sure you have adequate backup procedures before converting from a single-instance Oracle database to RAC. This may involve the use of RMAN, transportable tablespaces or the RMAN CONVERT utility.
   

• You must take into consideration the additional archiving considerations that apply in RAC environments. For example, the archive file format requires a thread number (this is done automatically for DBCA created RAC instances). In addition, the archived logs from all instances of a RAC database are required for media recovery. This means that if you archive to a file and you do not use a cluster file system, then a method of accessing the archive logs from all nodes on which the cluster database has instances, is required (such as NFS) where file systems are not shared.

Let's look at the actual conversion procedure from single-instance to RAC on Oracle Database 10g.

Converting from Single-Instance to 10g RAC

The conversion from single-instance Oracle databases to RAC can be difficult with 10g since Oracle has added many new features such as CRS, Virtual IP management and GRID control, therefore it is strongly recommended that you use the Database Configuration Assistant (DBCA) to convert from a single-instance to Oracle database 10g RAC. Use of the DBCA utility provides the following benefits:

1. Automation of the configuration of the control file attributes.
    

2. Creation of the needed undo tablespaces and the redo logs.
    

3. Makes the initialization parameter file entries for cluster-enabled environments.
    

4. Configuration of the Oracle Net Services.
    

5. Configuration of the Cluster Ready Services (CRS) resources.
    

6. Configuration of the EM (Grid control) and SRVCTL to allow for RAC database management.

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