The old quipu X.500 directory originally used a similar approach (load to ram at startup, writes go to ram+disk, reads+searches come from ram). You get durabil

The old quipu X.500 directory originally used a similar approach (load to ram at startup, writes go to ram+disk, reads+searches come from ram). You get durability and run-time performance, but there can be appreciable downtime during the startup phase.