A distributed spin-down algorithm for an object-based storage device with write redirection

We present a distributed spin-down algorithm for conserving energy in an object-based storage device (OSD) cluster. It differs from traditional spin-down algorithms in that it is cooperative—the decision to spin-down an OSD considers not only its own internal state, but also the state of the other OSDs. Each OSD executes an instance of the spin-down algorithm and adapts to the overall workload. To maximize energy saving, a write request for a spundown OSD may be redirected to another OSD, and a read request for a redirected object will be redirected to the OSD storing that object, thus increasing the spin-down duration of a spun-down OSD. 1