Method of determining lower bound for replication cost

摘要

An embodiment of a method of determining a lower bound for a minimum cost of placing data objects onto nodes of a distributed storage system begins with a first step of assigning a placement of a data object to a node and a time interval which meets a benefit criterion. Assignment of the placement of the data object to the node and the time interval comprises assigning the placement of the data object to a node-interval. The method continues with a second step of continuing to assign additional placements of the data object to other node-intervals which each meet the benefit criterion until a performance reaches a performance threshold. The method performs the first and second steps for each of the data objects. The method concludes with a step of calculating a sum of storage costs and creation costs for the placement and the additional placements of the data objects. According to another embodiment, the data object placed in the first and second steps is chosen on a basis of a triplet of the data object, the node, and the interval which meets the benefit criterion.