A redundant array of independent disks, RAID, storage system, comprising: a RAID master controller adapted to receive a RAID request; a first storage device and a second storage device, each of which comprising a RAID controller (210, 212) that includes a RAID request processing unit (230, 232) and a RAID request distributing unit (250, 252), wherein each of the first storage device and the second storage device comprises a flash memory configured to store data as stripes (310, 312) into a plurality of data storage regions (300, 302), the RAID request processing unit of the first storage device being adapted to receive (S602, S800) the RAID request from the RAID master controller, wherein the RAID request is a request to update old data stored in said first storage device with new data, to determine whether distribution of a RAID sub-request that is derived from, but different from the RAID request is necessary, and to directly process the received RAID request, upon determining that the distribution is not necessary; and upon determining that the distribution of the RAID sub-request is necessary, the RAID request distributing unit of the first storage device being adapted to communicate, via a direct network connection between the first storage device and the second storage device, the RAID sub-request with XOR data to the RAID controller of the second storage device, wherein the RAID sub-request is a request to update parity data derived from the old data and stored in the second storage device, wherein the XOR data is generated by the RAID controller of the first storage device by performing an XOR operation on the old data and the new data. a RAID master controller adapted to receive a RAID request; a first storage device and a second storage device, each of which comprising a RAID controller (210, 212) that includes a RAID request processing unit (230, 232) and a RAID request distributing unit (250, 252), wherein each of the first storage device and the second storage device comprises a flash memory configured to store data as stripes (310, 312) into a plurality of data storage regions (300, 302), the RAID request processing unit of the first storage device being adapted to receive (S602, S800) the RAID request from the RAID master controller, wherein the RAID request is a request to update old data stored in said first storage device with new data, to determine whether distribution of a RAID sub-request that is derived from, but different from the RAID request is necessary, and to directly process the received RAID request, upon determining that the distribution is not necessary; and upon determining that the distribution of the RAID sub-request is necessary, the RAID request distributing unit of the first storage device being adapted to communicate, via a direct network connection between the first storage device and the second storage device, the RAID sub-request with XOR data to the RAID controller of the second storage device, wherein the RAID sub-request is a request to update parity data derived from the old data and stored in the second storage device, wherein the XOR data is generated by the RAID controller of the first storage device by performing an XOR operation on the old data and the new data.