VoltDB Community Edition uses synchronous intra-cluster replication, as well as rolling on-disk snapshots for durability. The Enterprise Edition adds a synchro

VoltDB Community Edition uses synchronous intra-cluster replication, as well as rolling on-disk snapshots for durability. The Enterprise Edition adds a synchronous or asynchronous command log (a logical journal) as well as asynchronous multi-cluster replication. The VoltDB blog has a series of posts covering command logging in detail: http://voltdb.com/company/blog/intro-voltdb-command-logging http://voltdb.com/company/blog/intro-voltdb-command-logging http://voltdb.com/company/blog/voltdb-command-logging-replay http://voltdb.com/company/blog/voltdb-command-logging-replay http://voltdb.com/company/blog/voltdb-command-logging-options http://voltdb.com/company/blog/voltdb-command-logging-option... In short, VoltDB offers tunable durability from single-node purely in-memory, all the way up to synchronous disk storage on multiple local nodes and multiple asynchronous copies in another data center. All options are fully transactional. All options are extremely performant. We've worked very hard to make durability and performance not mutually exclusive. We have internally achieved six-figure TPS numbers using synchronous writes (requires a disk controller with a BBU, or a decent SSD).