Patent ID: 7831741

Claim:
An indexing device for a data storage system which comprises a plurality of data storage devices, the indexing device comprising: a memory module; an I/O processing module, according to a target data storage device, for generating an I/O descriptor and an I/O descriptor index number corresponding to the I/O descriptor, wherein the I/O descriptor index number is corresponding to a device ID number and a queued command tag number of the target data storage device, the I/O processing module storing the I/O descriptor in the memory module, wherein the target data storage device is capable of buffering N queued I/O commands, where N is a positive integer, and the queued command tag number is an integer between 0 and N−1; and a controller module for generating an I/O command by retrieving the I/O descriptor from the memory module and transmitting the I/O command to the target data storage device; wherein after receiving from the target data storage device an information packet with the queued command tag number and a second connection request data frame with the device ID number, the controller module calculates the I/O descriptor index number by multiplying the device ID number by N and adding the queued command tag number.