10. The system of claim 9 , wherein the operations further comprise: maintaining a persistent, transactionally recoverable structure that stores the virtual-index-epoch map.
10. The system of claim 9 , wherein the operations further comprise: maintaining a persistent, transactionally recoverable structure that stores the virtual-index-epoch map. 12. The system of claim 10 , wherein the operations further comprise: maintaining the virtual-index-epoch map by at least one of creating and deleting virtual-index-epoch numbers from the virtual-index-epoch map.