Abstract: Update anywhere-anytime-anyway transactional replication has unstable behavior as the workload scales up: a ten-fold increase in nodes and traflc gives a thousand fold increase in deadlocks or reconciliations. Master copy replica-tion (primary copyj schemes reduce this problem. A simple analytic model demonstrates these results. A new two-tier replication algorithm is proposed that allows mobile (disconnected) applications to propose tentative update trans-actions that are later applied to a master copy. Commutative update transactions avoid the instability of other replication schemes. 1.