To enable Oracle ASM to discover and access Exadata grid disks, you must configure the ASM_DISKSTRING initialization parameter.

Exadata grid disks are specified by using a discovery string with the following format:

o/<cell_IP_pattern>/<griddisk_name_pattern>

In the discovery string:

• <cell_IP_pattern> identifies Exadata storage server IP address (as listed in the cellip.ora file).

• <griddisk_name_pattern> identifies grid disks by name.

The wildcard character (*) can be used to expand the <cell_IP_pattern> and <griddisk_name_pattern> values.

For example, the following ASM_DISKSTRING setting discovers all Exadata grid disks on all cells specified in the cellip.ora file:

ASM_DISKSTRING = 'o/*/*'

You can use a more specific setting to discover a subset of grid disks. For example, the following ASM_DISKSTRING setting discovers only the grid disks with names that begin with DATA:

ASM_DISKSTRING = 'o/*/DATA*'

You can change the ASM_DISKSTRING initialization parameter when the Oracle ASM instance is running with the SQL ALTER SYSTEM command. If you edit the ASM_DISKSTRING initialization parameter in the initialization parameter file when the Oracle ASM instance is running, then the Oracle ASM instance must be shut down and restarted for the change to take effect.