Patent ID: 7574623

Claim:
A machine-implemented method, comprising: predicting an imminent failure of a particular mass storage device in a redundancy group of mass storage devices; responsive to predicting the imminent failure of the particular mass storage device, automatically initiating a device-to-device copy operation to copy data from the particular mass storage device to a spare mass storage device; during the device-to-device copy operation, receiving a client-initiated read request directed to a storage area on the particular mass storage device, and forwarding the client-initiated read request to the particular mass storage device for servicing; upon receiving, from the particular mass storage device, an error indicating the particular mass storage device failed to service the client-initiated read request, determining whether data from the storage area of the particular mass storage device has been copied to the spare mass storage device; if data from the storage area of the particular mass storage device has been copied to the spare mass storage device, forwarding the client-initiated read request to the spare mass storage device for servicing; and upon completion of the device-to-device copy operation, reconfiguring the redundancy group to replace the particular mass storage device in the redundancy group with the spare mass storage device.