Oracle Database Tips by Donald Burleson

Oracle10g Grid Computing with RAC
Chapter 5 - Preparing Shared Storage

Cluster Volume Management

Placing the shared disks or LUNS from the shared storage array into the Volume Manager control. When the LUNS are placed under the VM control, they are known as VM disks.

• Creating the Disk Groups - the disk groups that contain the database application must be available to all nodes in the cluster. A disk group allows disks, volumes, and file systems that are relevant to a single database to be arranged into a logical collection for easy administration.
   

• Creating volumes with the appropriate layout (mirror, stripe. etc.) and size from the disk group storage pool. Volumes are flexible objects that can be extended or modified.
   

• Making file systems from the volumes and mounting them for database use. Volumes can also be used for database applications, in which case they are referred to as raw devices.

It is important to understand that volumes are the basic storage components that an Oracle database utilizes. The volumes, as created by the CVM, are accessible by all members or nodes of the cluster. This is an important distinction in the RAC environment. A volume can be accessed either directly by the RAC database as a raw partition, or through mounted file systems such as a CFS, as shown in Fig. 15.17