VoltDB replicates to k nodes so you can choose the level of durability. Combined with UPSes in separate parts of the datacenter, it's durable in some senses. (I'd be more concerned with a kernel or app bug that crashes the system, if there wasn't a "save RAM on unclean boot".
This only applies to the commercial version, though. The open source one ditched that feature.
This only applies to the commercial version, though. The open source one ditched that feature.