2016 USENIX Annual Technical Conference (USENIX ATC '16)

Cold storage devices such as tape and optical discs are a good solution for reducing the total cost of owner- ship for storing data. However, there is a drawback in that media and drives are separated, and placing me- dia into drives when accessing data needs a few min- utes of time. Though placing correlated data together in the same medium reduces media exchange, multi- dimensional searches disrupt it. We propose two ap- proaches which replicate data and place them in different layout for solving the problem. By concentrating on rela- tive latency reduction or utilizing replicas originally gen- erated for avoiding data loss, our method achieves high latency reduction with restricted capacity efficiency loss. A simulation result shows 31% average relative latency reduction with capacity efficiency remaining at 91%.