Patent ID: 8499184

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