Patent ID: 8495406

Claim:
A storage system, comprising: a primary power supply; a secondary power supply; at least one storage volume; a storage volume controller coupled to the at least one storage volume, the primary power supply, and the secondary power supply, wherein the storage volume controller comprises a cache memory and a non-volatile memory coupled to the cache memory, the storage volume controller for: detecting a loss of power from the primary power supply; preventing receipt of input/output commands in response to detecting the loss of power, copying contents in the cache memory to the non-volatile memory utilizing the secondary power supply in response detecting the loss of power, detecting resumption of the primary power supply, charging the secondary power supply utilizing the primary power supply, copying the content of the non-volatile memory back to the cache memory in response to detecting the resumption of the primary power supply, transmitting the content of the cache memory to the at least one storage volume while continuing prevention of receipt of input/output commands at the cache memory, detecting that charge stored on the secondary power supply exceeds a first threshold amount of charge required to copy the content of the cache memory to the non-volatile memory by a predetermined amount, enabling receipt of input/output commands at a reduced rate in response to detecting that the charge stored on the secondary power supply exceeds the first threshold amount of charge, the reduced rate dependent upon the amount of charge stored on the secondary power supply and the reduced rate decreasing over time as the secondary power supply charges, pursuant to enabling receipt of the input/output commands at the reduced rate, locking a portion of the cache memory from use, detecting that the charge stored on the secondary power supply has reached a second threshold amount, and allowing receipt of input/output commands at a full rate at the cache memory in response to detecting that the charge stored on the secondary power supply has reached the second threshold amount.