As part of configuring each Oracle Exadata Database Service on Cloud@Customer VM cluster, the storage space inside the Exadata Storage Servers is configured for use by Oracle Automatic Storage Management (ASM).

By default, the following ASM disk groups are created:

• The DATA disk group is primarily intended for the storage of Oracle Database data files. Also, a small amount of space is allocated from the DATA disk group to support the shared file systems that are used to store software binaries (and patches) and files associated with the cloud-specific tooling. You should not store your own data, including Oracle Database data files, backups, trace files, and so on, inside the system-related ACFS file systems.
• The RECO disk group is primarily used for storing the Fast Recovery Area (FRA), which can be used to provide a local store for files related to backup and recovery. By default, the FRA is used to store archived redo log files and the backup control file. If you configure your VM cluster with the option to allocate storage for local backups, then you can use the FRA as a database backup destination. Finally, if you enable flashback features on a database, then the FRA is used to store the flashback logs.

In addition, you can choose to create the SPARSE disk group. The SPARSE disk group is required to support Exadata snapshot functionality. Exadata snapshots enable space-efficient clones of Oracle databases that can be created and destroyed very quickly and easily. Snapshot clones are often used for development, testing, or other purposes that require a transient database. For more information about Exadata snapshot functionality, see Setting Up Oracle Exadata Storage Snapshots in the Oracle Exadata System Software User's Guide.

Select the storage option that best meets your planned use case on your Oracle Exadata Storage Servers.

As an input to the virtual machine (VM) cluster creation process, you must choose options that determine how storage space in the Oracle Exadata Storage Servers is allocated to the Oracle ASM disk groups. Your choices profoundly affect how storage space in the Exadata Storage Servers is allocated to the ASM disk groups. Consider which option best meets your needs:

• Allocate Storage for Exadata Snapshots

  If you select this option, then the SPARSE disk group is created, and less space is allocated to the DATA and RECO disk groups. If you do not select this option, then the SPARSE disk group is not created, and you cannot use Exadata snapshot functionality.

• Allocate Storage for Local Backups

  If you select this option, then more space is allocated to the RECO disk group to accommodate local backups to Oracle Exadata storage. If you do not select this option, then more space is allocated to the DATA disk group, but you cannot use local Oracle Exadata storage as a backup destination for any databases in the VM cluster.

Determine the storage allocation between the DATA, RECO, and SPARSE disk groups for Oracle Exadata Storage Servers.

Exadata Cloud@Customer X8M systems use the following file system organization on the virtual machines. To plan for local storage allocation on the virtual machines please refer to Estimating How Much Local Storage You Can Provision to Your VMs.