Method and apparatus for maintaining cache coherency in a storage system

A controller system for maintaining cache coherency, comprising:

• a disk array,
• a first controller, coupled to the disk array, for selecting a mirror cache line on a second controller;
• and
• an interface for mirroring the data from a first controller cache line to the second controller cache line;
• wherein a message is sent from the first controller to the second controller informing the second controller about cache meta data associated with the mirror cache line.

An article of manufacture comprising a program storage medium readable by a computer, the medium tangibly embodying one or more programs of instructions executable by the computer to perform a method for maintaining cache coherency, the method comprising:

• selecting a mirror cache line in a second controller to copy data into;
• mirroring the data from a cache line in a first controller to the mirror cache line in the second controller;
• and
• sending a message from the first controller to the second controller informing the second controller of cache meta data associated with the mirror cache line.

A storage system for maintaining cache coherency, comprising:

• means for selecting a mirror cache line in a second controller to copy data into;
• means for mirroring the data from a cache line in a first controller to the mirror cache line in the second controller;
• and
• means for sending a message from the first controller to the second controller informing the second controller of cache meta data associated with the mirror cache line.