Memory system with hot swapping function and method for replacing defective memory module

A method for replacing a defective memory module in a memory system, with a hot swapping function, being a memory system in which one end of a row of a plurality of memory modules sequentially connected to one another in series is connected to a first input-output section of a memory controller and another end of said row of memory modules is connected, with a spare memory module connected in series, to a second input-output section of said memory controller and said memory controller ordinarily gains access to each of said memory modules making up the memory module row to read or write data in series, said method comprising:

• exerting control so that, when a failure occurs in any one of said memory modules making up said memory module row, said memory controller disconnects the defective memory module from the memory modules in a succeeding stage and connects the memory module in the succeeding stage to said second input-output section through said spare memory module;
• exerting control so that, with said defective memory module disconnected from the memory modules in succeeding stages, data stored in said defective memory module is copied into said spare memory module and, after completion of the copying, said defective memory module is replaced with said spare memory module and said memory controller gains access to each of said memory controllers from said second input-output section;
• and
• exerting control so that, after the replacement of said defective memory module, data stored in said spare memory module is copied into the memory module used instead of said defective memory module and, after completion of the copying, with said memory module used instead of said defective memory module connected to memory modules in next and onward stages, said memory controller gains access to each of said memory modules from said first input-output section thereafter.