Patent ID: 8135906

Claim:
A Redundant Array of Independent Disks (RAID) storage controller that interfaces with a host computer and a RAID storage volume, the RAID storage controller comprising: a disk drive management module that configures the RAID storage volume from a first plurality of disk drives and that controls read and write operations requested by the host computer; and a storage capacity management module that increases storage capacity via a transfer of data from the RAID storage volume to at least one expansion disk drive that comprises a storage capacity greater than at least one disk drive of the RAID storage volume, wherein the RAID storage volume comprises the same RAID level after transfer of the data to the at least one expansion disk drive, wherein the transfer of the data from the RAID storage volume to the at least one expansion disk drive occurs during the read and write operations to the RAID storage volume, wherein the transfer of the data from the RAID storage volume comprises duplicating incoming write operations such that they are forwarded to the plurality of disk drives and forwarded to the at least one expansion disk drive, and wherein the storage capacity management module detects a failure of at least one of the first plurality of disk drives during the transfer of data, wherein the storage capacity management module continues host read operations to the remaining disk drives of the first plurality of disk drives responsive to detecting the failure, wherein the storage capacity management module continues duplicating incoming write operations such that they are forwarded to the plurality of disk drives and forwarded to the at least one expansion disk drive responsive to detecting the failure, and wherein the storage capacity management module takes the first plurality of disk drives off-line from read and write operations directed to the RAID storage volume upon completion of the transfer of data.