You can create an Oracle ASM disk group using one of the following storage resources:
Disk Partition
A disk partition can be the entire disk drive or a section of a disk drive. However, the Oracle ASM disk cannot be in a partition that includes the partition table because the partition table would be overwritten.
A LUN is a disk presented to a computer system by a storage array. Oracle recommends that you use hardware RAID functionality to create LUNs. Storage hardware RAID 0+1 or RAID5, and other RAID configurations, can be provided to Oracle ASM as Oracle ASM disks.
Logical Volume
A logical volume is supported in less complicated configurations where a logical volume is mapped to a LUN, or a logical volume uses disks or raw partitions. Logical volume configurations are not recommended by Oracle because they create a duplication of functionality. Oracle also does not recommended using logical volume managers for mirroring because Oracle ASM provides mirroring.
An Oracle ASM disk group can be created from NFS files, including Oracle Direct NFS (dNFS), such as whole disks, partitions, and LUNs. The NFS files that are provisioned to a disk group may be from multiple NFS servers to provide better load balancing and flexible capacity planning.
You can use Direct NFS to store data files, but is not supported for Oracle Clusterware files. To install Oracle Real Application Clusters (Oracle RAC) on Windows using Direct NFS, you must also have access to a shared storage method other than NFS for Oracle Clusterware files.
Oracle Grid Infrastructure Installation Guide for your operating system for information about Oracle Direct NFS
Oracle ASM Dynamic Volume Manager (Oracle ADVM) volumes and Oracle Automatic Storage Management Cluster File System (Oracle ACFS) file systems are currently not supported on disk groups that have been created from NFS or Common Internet File System (CIFS) files. However, Oracle ACFS file systems may be exported as NFS or CIFS file systems to network clients in some cases. Samba/CIFS clients on Windows cannot use ACLs when interfacing with Oracle ACFS Linux, Solaris, or AIX servers.
Mounting loopback file systems over Oracle ACFS files is not supported.
Block or raw devices are not supported by Oracle Universal Installer (OUI) or Database Configuration Assistant (DBCA).
The procedures for preparing storage resources for Oracle ASM are:
Identify or create the storage devices for Oracle ASM by identifying all of the storage resource device names that you can use to create an Oracle ASM disk group. For example, on Linux systems device names are typically presented from the /dev directory with the /dev/device_name_identifier name syntax.
Change the ownership and the permissions on storage device resources.
For example, the following steps are required on Linux systems:
Change the user and group ownership of devices, such as grid:asmadmin
For information about Oracle ASM privileges, see "About Privileges for Oracle ASM".
Change the device permissions to read/write
After you have configured Oracle ASM, ensure that disk discovery has been configured correctly by setting the ASM_DISKSTRING initialization parameter. For information about the ASM_DISKSTRING parameter, see "ASM_DISKSTRING".
Setting the ownership to oracle:dba is one example that corresponds to the default settings. A nondefault installation may require different settings. In general, the owner of the disk devices should be the same as the owner of the Oracle binary software. The group ownership should be OSDBA of the Oracle ASM instance, which is defined at installation. For information about Oracle ASM privileges, see "About Privileges for Oracle ASM".
For detailed information about preparing disks for an Oracle ASM installation, refer to your platform-specific installation guide for Oracle Database, Oracle Clusterware, and Oracle Real Application Clusters (Oracle RAC).