re the questions about replication across datacenters, see: http://code.google.com/events/io/sessions/TransactionsAcrossDatacenters.html http://code.google.com

re the questions about replication across datacenters, see: http://code.google.com/events/io/sessions/TransactionsAcrossDatacenters.html http://code.google.com/events/io/sessions/TransactionsAcross... it discusses both app engine's approach and the underlying factors and tradeoffs that apply to any similar system. for the executive summary, see slide 33 from: http://snarfed.org/space/transactions_across_datacenters_io.html http://snarfed.org/space/transactions_across_datacenters_io....