A data storage system wherein a data controlling director examines the contents of the tag to determine whether requested read data exists in a local cache memory having this data controlling director or in some other local memory cache, or in a disk drive coupled to this data controlling director; and if the requested read data does exist in the local cache memory having this data controlling director, or in the disk drive coupled to director; the data controlling director sends a copy to the local cache memory of the read request receiving director; updates its tag to show a shared copy will reside in the requesting director's local cache memory; and also sends a message to the read requesting director indicating the data is available for storage in the local cache memory on said one of the plurality of first director/memory boards having the read request receiving director.