Oracle 11g ASM on AIX with Real Applications Clusters (RAC)

Prior to the release of Oracle Database Server 10g, database administrators had to choose between raw logical volumes or filesystems to house their data files.

The decision to implement one or the other was always a compromise, as use of raw logical volumes may yield the best performance, but filesystems are easier to administer. The choice of filesystems offers many features for the dba.

Since the unit of storage allocation is a filesystem, and the filesystem is owned by the Oracle user, the DBA can allocate additional data files as needed.

Oracle’s autoextend feature can also be used to increase the space allocation for data files when necessary, and free space can be easily seen at the system level to be used with capacity planning tools.

When it comes to backups, the data copy can also take place at the system level, backing up only used data.

When raw logical volumes are used, on the other hand, a logical volume must be allocated for each database file.

Adding or resizing a logical volume must be performed by the systems administrator.

For backups, either RMAN must be used, or the entire raw logical volume must be written to the backup media, including unused sectors.

In Oracle 10g, a new choice for data file storage was introduced, called Automatic Storage Management (ASM).

Built on raw device files, ASM offers the performance of raw logical volumes, with the configuration flexibility of filesystems.

The purpose of this paper is to provide information about the requirements and considerations for ASM implementation for a Real Applications Cluster (RAC) environment using the AIX operating system.

Although ASM may also be used in a single-instance environment, this document will only discuss ASM in the context of RAC.

See link below

11gRAC_ASM_1

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