The ASM Balance alarm is raised when the IO distribution across the disks in an ASM (Automatic Storage Management) disk group shows a persistent and significant imbalance. Oracle distributes blocks across the disks in a disk group with the intention of spreading IO demand evenly and avoiding "hot disks".
This strategy is not always successful, and manual rebalancing may sometimes be required.
If you encounter persistent ASM balance alarms, consider the following:
Tip: For more information on the Oracle ASM storage management solution, see the ASM drilldown.