You can add disks to a disk group to increase the storage space in a disk group. If you add multiple disks in a single operation, then Oracle ASM rebalances the disk group to evenly distribute the data on all disks, including the newly added disks.
You can control the power of a rebalance operation with the setting of the Rebalance Power. The higher the number, the faster the rebalance operation completes. Lower numbers cause rebalancing to take longer, but consume fewer processing and I/O resources. This leaves these resources available for the database. The default value of 1 minimizes disruption to the database.
A value of 0 blocks the rebalance operation. Manual or automatic rebalance can then occur later. You might want to postpone rebalancing until there are fewer demands on the database, or when you have completed all of your disk group changes.
For information about controlling rebalance operations, refer to "Manually Rebalancing Disk Groups" and "Tuning Rebalance Operations". For information about rebalance power settings and the ASM_POWER_LIMIT initialization parameter, refer to "ASM_POWER_LIMIT".
To add one or more disks to a disk group:
Access the Oracle Automatic Storage Management home page.
For instructions, refer to "Accessing the Oracle Automatic Storage Management Home Page".
Click the Disk Groups link to display the Disk Groups property page.
If the Oracle ASM Login page appears, then log in as the SYS user, connecting as SYSASM. Provide the SYS password for the Oracle ASM instance. This password was set up when the Oracle ASM instance was created.
Click a link in the Name column to select the disk group to which you want to add disks. The Disk Group page similar to the page in Figure 7-6 appears, displaying a list of disks that are in the disk group.
Click Add and Oracle Enterprise Manager displays the Add Disks page. This page displays a list of Oracle ASM disks that are available to be added to the disk group. This includes disks with the header status of CANDIDATE, PROVISIONED, or FORMER, and so on.
To display not only disks that are available to be added to a disk group, but all of the Oracle ASM disks, including disks that belong to a disk group (header status = MEMBER), select All Disks from the Select Member Disks drop-down list on the right hand side of the page. Oracle Enterprise Manager re-displays the page with the complete list of Oracle ASM disks that were discovered by the Oracle ASM instance.
Optionally change the rebalance power by selecting a value from the Rebalance Power list.
Select disks as follows:
Check the box to the left of each disk to be added to the disk group.
To force the inclusion of a disk in the disk group, select the Force Reuse box in the right-most column.
The Force Reuse box causes the disk to be added to the disk group even if the disk belongs to another disk group and has valid database data. The existing data is then lost. You must be certain that you are selecting a disk that can legitimately be added to the disk group. Refer to "Adding Disks to a Disk Group" for an example of the FORCE option.
Optionally enter an Oracle ASM disk name for each disk. Oracle ASM provides a name if you do not.
Click OK to add the selected disks.
For more information about modifying disk group properties, see "Altering Disk Groups".