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