  Deferred update replication (DUR) is an established approach to implementing
highly efficient and available storage. While the throughput of read-only
transactions scales linearly with the number of deployed replicas in DUR, the
throughput of update transactions experiences limited improvements as replicas
are added. This paper presents Parallel Deferred Update Replication (P-DUR), a
variation of classical DUR that scales both read-only and update transactions
with the number of cores available in a replica. In addition to introducing the
new approach, we describe its full implementation and compare its performance
to classical DUR and to Berkeley DB, a well-known standalone database.
