Provide the name of the initial disk group you configure for database files in the Disk Group Name field.
The Disks table displays existing disk groups. Select the disk group that you want to use for database file storage. Database files require a minimum of 3.3 MB of available disk space.
If you do not see displayed the disk group you want to use, then click Refresh to ensure that all available disk groups are displayed.
For additional information, review the following sections:
An ASM disk group consists of multiple disk partitions. Disk groups are configured during Oracle Grid infrastructure installation, and configured after installation with the SYSASM privilege using asmcmd or SQL create diskgroup commands.
The disk group is the fundamental object that ASM manages. Each disk group contains the metadata that is required for the management of space in the disk group. Files are allocated from disk groups. Any ASM file is completely contained within a single disk group. However, a disk group might contain files belonging to several databases and a single database can use files from multiple disk groups. For most installations you need only a small number of disk groups, usually two, and rarely more than three. Disk group components include disks, files, and allocation units.
Redundancy, or mirroring, is the process of replicating the contents of a file in other files. Redundancy protects data integrity by storing copies of data on multiple disks. The disk group type determines the mirroring levels with which Oracle creates files in a disk group.
When you create a disk group, you specify an ASM disk group type based on one of the following three redundancy levels:
High: Three-way mirroring
Normal: Two-way mirroring
External: Choosing not to use ASM mirroring of files, commonly when you provide mirroring using another technology, such as a Redundant Array of Independent (or Inexpensive) Disks (RAID).
The disk group type determines the mirroring levels with which Oracle creates files in a disk group. The redundancy level controls how many disk failures are tolerated without dismounting the disk group or losing data.