1. A method for managing data storage servers, comprising: establishing a cluster of back-end servers organized into nodes, every node in the cluster having a node identifier that is unique in the cluster, every back-end server in any node mirroring every other back-end server in the same node; establishing a predefined set of ultimate identifiers for nodes that could be created in the cluster; and storing every new data object on the cluster on a particular node, the particular node having a particular node identifier that identifies a subset of the set of ultimate identifiers, and providing for the object a universal identifier that combines (i) an object identifier that is unique on the particular node and (ii) a server identifier, where the server identifier is one of the ultimate identifiers in the subset, and where the node identifiers for nodes existing in the cluster at any one time identify non-overlapping subsets of the set of ultimate identifiers.