Occasionally, Oracle Automatic Storage Management (Oracle ASM) must perform a data rebalance operation. A data rebalance operation may be required for various reasons, including:

• To resynchronize data after a storage server rolling update.

• To restore the desired data redundancy after a hard disk failure.

• To maintain even data distribution after adding a storage server.

Oracle ASM uses the asm_power_limit parameter to control the resource limit for data rebalance operations. Setting asm_power_limit to a low value provides minimal resources, which enables the operation to proceed slowly with minimal disruption to other database workloads. Setting asm_power_limit to a high value offers more resources, resulting in quicker data rebalance operations. However, this can adversely impact other database workloads.

Oracle Exadata System Software release 25.1.0 contains enhancements and algorithms that dynamically tune asm_power_limit to enable data rebalance operations to run as fast as possible without negatively impacting other database workloads.

Under this capability, Oracle Exadata System Software continuously monitors I/O performance and automatically raises the asm_power_limit value when the system has plenty of available I/O bandwidth. Likewise, when the system detects client database workloads, it automatically lowers the asm_power_limit value to prioritize those workloads.