Online storage capacity expansion of a raid storage system

A method of expanding storage capacity in a Redundant Array of Independent Disks (RAID) storage system having a RAID storage controller and having a first plurality of disk drives configured as a RAID storage volume, wherein the RAID storage controller is in communication with the RAID storage volume, the method comprising:

• communicatively coupling at least one expansion disk drive to the RAID storage controller;
• initiating a storage capacity management module in response to communicatively coupling the at least one expansion disk drive to the RAID storage controller;
• copying data from the RAID storage volume, via the storage capacity management module, to the at least one expansion disk drive, wherein the copying comprises performing Remote Direct Memory Access (RDMA) from at least one disk drive of the first plurality of disk drives to the at least one expansion disk drive;
• while copying the data from the RAID storage volume to the at least one expansion disk drive, performing read and write operations to the RAID storage volume;
• detecting a failure of at least one of the first plurality of disk drives during the copying;
• continuing host read operations to the remaining disk drives of the first plurality of disk drives responsive to detecting the failure;
• continuing duplicating incoming write operations such that they are forwarded to the first plurality of disk drives and forwarded to the at least one expansion disk drive responsive to detecting the failure;
• and
• taking the first plurality of disk drives off-line from read and write operations directed to the RAID storage volume upon completion of the copying data.

A non-transitory computer readable medium for expanding storage capacity in a Redundant Array of Independent Disks (RAID) storage system having a RAID storage controller and having a first plurality of disk drives configured as a RAID storage volume, wherein the RAID storage controller is in communication with the RAID storage volume, the computer readable medium including software instructions that, when executed by a computer processor, direct the computer processor to:

• communicatively couple at least one expansion disk drive to the RAID storage controller;
• initiate a storage capacity management module in response to communicatively coupling the at least one expansion disk drive to the RAID storage controller;
• copy data from the RAID storage volume, via the storage capacity management module, to the at least one expansion disk drive, wherein copying data from the RAID storage volume comprises performing Remote Direct Memory Access (RDMA) from at least one disk drive of the first plurality of disk drives to the at least one expansion disk drive;
• while copying the data from the RAID storage volume to the at least one expansion disk drive, perform read and write operations to the RAID storage volume;
• detecting a failure of at least one of the first plurality of disk drives during the copying;
• continuing host read operations to the remaining disk drives of the first plurality of disk drives responsive to detecting the failure;
• continuing duplicating incoming write operations such that they are forwarded to the first plurality of disk drives and forwarded to the at least one expansion disk drive responsive to detecting the failure;
• and
• taking the first plurality of disk drives off-line from read and write operations directed to the RAID storage volume upon completion of the copying.

A Redundant Array of Independent Disks (RAID) storage controller that interfaces with a host computer and a RAID storage volume, wherein the RAID storage controller configures the RAID storage volume from a first plurality of storage elements and wherein the RAID storage controller controls read and write operations requested by the host computer, the RAID storage controller comprising:

• a storage capacity management module that increases storage capacity via a transfer of data from the RAID storage volume to at least one expansion storage element that comprises a storage capacity greater than at least one storage element 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 storage element, wherein the transfer of the data from the RAID storage volume to the at least one expansion storage element occurs during the read and write operations to the RAID storage volume, and 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, wherein the storage capacity management module detects a failure of at least one of the first plurality of storage elements during the transfer of data, wherein the storage capacity management module continues host read operations to the remaining storage elements of the first plurality of storage elements 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 storage elements and forwarded to the at least one expansion storage element 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.