Oracle Database Tips by Donald Burleson

Oracle10g Grid Computing with RAC
Chapter 5 - Preparing Shared Storage

ASM Instance Background Processes

• RBAL - coordinates rebalance activity for disk groups.
   

• ORB0, ORB1… - These perform the actual rebalance data extent movements. There can be many of these at a time.

Any database instance that is using an ASM disk group will contain a background process called OSMB. The OSMB process is responsible for communicating with the ASM instance. The RBAL background process within in database instance, called RBAL (just like in the ASM Instance), performs a global open on ASM disks. A global open means that more than one database instance can be accessing the ASM disks at a time.

Installation of ASM

In Oracle Database 10g, the Oracle Universal Installer (OUI) will always install ASM when the database software is installed. The Database Configuration Assistant (DBCA) determines if an ASM instance already exists, and if not, then you will be given the option of creating and configuring an ASM instance as part of the installation. If an ASM instance already exists, then it will be used by default. DBCA automatically configures your ASM instance parameter file and password file.

DBCA eases the configuring and creation of your database, while EM provides an integrated approach for managing both your ASM instance and database instance.