The present invention is storage apparatus where an intermediary device is arranged between {HEAD ~ a controller} and a plurality of disk devices of {TAIL ~ different performances} arranged in a hierarchical manner 
The present invention is storage apparatus where an intermediary device is arranged between { HEAD ~ a controller } and a plurality of disk devices of { TAIL ~ different performances } arranged in a hierarchical manner
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH