Patent ID: 8185691

Claim:
A method for caching data in a storage array having two controllers and an array of persistent storage devices, comprising: receiving a data write request and associated write data from an external host; a first controller initiating a write transaction in response to the data write request, the write transaction preventing a second controller from accessing the persistent storage devices during the write transaction; the first controller storing the write data in at least one of the persistent storage devices in accordance with the write transaction; the first controller copying the write data to a first data cache, the first data cache under exclusive control of the first controller and not accessible to the second controller; after the write transaction completes, the first controller transmitting identification data identifying the write data to the second controller but not transmitting any of the write data itself to the second controller; the second controller identifying corresponding cached data in a second data cache in response to the identification data, the second data cache under exclusive control of the second controller and not accessible to the first controller; and the second controller invalidating the corresponding cached data in the second data cache.