Patent ID: 8131961

Claim:
A distributed storage system for storage of a data unit, comprising: a plurality of storage elements of unspecified system reliability; a public network interconnecting the plurality of storage elements; reliability index control continuously measuring a plurality of storage element reliability indexes which are associated with the plurality of storage elements and take into account the reliability of the plurality of storage elements and the reliability of the part of the public network connecting the plurality of storage elements; storage processing device for receiving a request to store the data unit according to a data unit availability index, reflecting an availability requirement of a user for the data unit, and for continuously monitoring data unit availability indices of stored data subject to changes in the plurality of storage element reliability indexes; and processing element for storing replicated copies of the data unit in at least one storage element, such that the data unit availability index is achieved; wherein the reliability index control calculates the storage element reliability indexes by being configured to: initialize the storage element reliability index of a new storage element with a default reliability index; increase the storage element reliability index by a first pre-defined value, if the storage element has participated in a first pre-defined number of successful storage transactions within a given time period; and decrease the storage element reliability index by a second pre-defined value, if the storage element has not participated in a second pre-defined number of successful storage transactions within a given time period.