Patent ID: 7269674

Claim:
A storage system comprising: a plurality of disk devices; an SAS expander coupled to the plurality of disk devices via first physical links having a first level transmission rate; and a controller coupled to the SAS expander via a second physical link having a second level transmission rate; wherein the first level transmission rate is lower than the second level transmission rate, wherein a plurality of RAID groups are configured in the plurality of disk devices, wherein the controller receives information of the first level transmission rate and the second level transmission rate, determines a multiplexing ratio based on the information of the first and second level transmission rates, multiplexes data to be stored in at least two disk devices, each included in a first RAID group of the plurality of RAID groups, of the plurality of disk devices by using time division multiplexing according to the multiplexing ratio, transmits a predetermined parameter to the SAS expander to indicate that subsequent data are multiplexed, and transmits multiplexed data to the SAS expander, and wherein when the SAS expander receives the predetermined parameter via the second physical link, the SAS expander demultiplexes the multiplexed data received after the predetermined parameter, and transmits demultiplexed data to the at least two disk devices included in the first RAID group to store the demultiplexed data in the at least two disk devices.