A peer-to-peer storage manager measures availability (liveness) of the various nodes in a peer-to-peer storage pool, and adjusts the storage of data within the pool to meet performance expectations based on this liveness information. Based on node liveness statistics, the peer-to-peer storage manager fine tunes storage up or down to efficiently allocate storage while maintaining service level objectives for retrieval time probabilities. Responsive to node liveness information, the peer-to-peer storage manager can dynamically adjust redundancy and/or determine which nodes on which to store data. The peer-to-peer storage manager can execute these storage modifications using rateless erasure codes that allow highly robust storage with only weakly synchronized directory update protocols.