Apparatus and method for controlling data flow between a computer and memory devices

Claim 1

In a system having a computer coupled to each of first and second level-one data routing controller means, said first and second data routing controller means each being coupled to first and second level-two data routing controller means, each of said first and second level-two data routing controller means being coupled to first and second groups of memory devices, respectively, through a switching circuit, a method comprising the steps of: determining in the second level-two data routing controller means that the first level-two data routing controller means has stopped functioning properly; providing, from within said second level-two data routing controller means, a first switching signal to said switching circuit; and switching, with said switching circuit, in response to said first switching signal, the coupling of said first group of memory devices from said first second-level data routing controller means to said second second-level data controller means.

Claim 5

An apparatus for linking a computer to a plurality of memory devices, comprising: at least first and second first-level data routing controller means for handling input/output storage communications with the computer; first and second buses coupling said first and second data routing controller means, respectively, to said computer; at least first and second second-level data routing controller means, each connected to each of said first-level data routing controller means and each other, for routing data from said first-level data routing controller means to first and second groups of said memory devices, respectively; switching means, coupled between said first and second second-level data routing controller means and said first and second groups of memory devices, for coupling said first and second groups of memory devices to said first second-level data routing controller means in response to first and second activate signals, respectively, from said first second-level data routing controller means, and for coupling said first and second groups of memory devices to said second second-level data routing controller means in response to second and first activate signals, respectively, from said second second-level data routing controller means; and each of said second-level data routing controller means, in the absence of a failure, providing said first activating signal to couple to only one of said groups of memory devices and including controller recovery system means for, responsive to a failure in the other second-level data routing controller means, providing said second activating signal to said switching means to couple to both of said groups of memory devices.

Claim 6

An apparatus for linking a computer to a plurality of memory devices, comprising: at least first and second first-level data routing controller means for handling input/output storage communications with the computer; first and second buses coupling said first and second data routing controller means, respectively, to said computer; at least first and second second-level data routing controller means, each connected to each of said first-level data routing controller means and each other, for routing data from said first-level data routing controller means to first and second groups of said memory devices, respectively; switching means, coupled between said first and second second-level data routing controller means and said first and second groups of memory devices, for coupling said first and second groups of memory devices to said first second-level data routing controller means in response to first and second activate signals, respectively, from said first second-level data routing controller means, and for coupling said first and second groups of memory devices to said second second-level data routing controller means in response to second and first activate signals, respectively, from said second second-level data routing controller means; and each of said second-level data routing controller means, in the absence of a failure, providing said first activating signal to couple to only one of said groups of memory devices and including controller recovery system means for, responsive to a failure in the other second-level data routing controller means, providing said second activating signal to said switching means to couple to both of said groups of memory devices.