It is important to understand the concepts of the key ASM components, which are listed as follows:
ASM instances
ASM disk groups
Mirroring and Failure groups
ASM disks
ASM files
An ASM instance is built on the same technology as an Oracle database instance. An ASM instance has a System Global Area (SGA) and background processes that are similar to those of Oracle Database. However, because ASM performs fewer tasks than a database, an ASM SGA is much smaller than a database SGA. In addition, ASM has a minimal performance effect on a server. ASM instances mount disk groups to make ASM files available to database instances; ASM instances do not mount databases.
ASM metadata is the information that ASM uses to control a disk group and the metadata resides within the disk group. ASM metadata includes the following information:
The disks that belong to a disk group
The amount of space that is available in a disk group
The filenames of the...