Patent ID: 7535832

Claim:
A method to set a signaling rate of a switch domain disposed in an information storage and retrieval system, comprising the steps of: supplying an information storage and retrieval system comprising a switch domain comprising a switch, two controllers, a plurality of data storage devices interconnected to said switch, a plurality of rate communication lines, wherein a different one of said plurality of rate communication lines interconnects each data storage device with one or both of said controllers, wherein said switch is capable of operating at a first signaling rate and at a second signaling rate, wherein said second signaling rate is greater than said first signaling rate; verifying the physical and electrical interconnections between said controllers and said plurality of data storage devices; designating a master controller; designating a slave controller; providing by said master controller a rate communication signal set to a first level on each of said plurality of rate communication lines; reading by said slave controller each of said plurality of rate communication lines; determining if each of said plurality of rate communication lines is set to said first level; if each of said plurality of rate communication lines is not set to said first level, generating an error message; if each of said plurality of rate communication lines is set to said first level, providing by said master controller a rate communication signal set to a second level on each of said plurality of rate communication lines; reading by said slave controller each of said plurality of rate communication lines; determining if each of said plurality of rate communication lines is set to said second level; if each of said plurality of rate communication lines is not set to said second level, generating an error message; if each of said plurality of rate communication lines is set to said second level, determining whether each of said plurality of data storage devices is first signaling rate capable, second signaling rate capable, or both first and second signaling rate capable; establishing a switch domain target operating speed; determining if said switch domain target operating speed comprises said first signaling rate; if said switch domain target operating speed comprises said first signaling rate; asserting first Device Control Code bits to each of said plurality of data storage devices; communicating by each of said plurality of data storage devices with said switch using said first signaling rate.