• low latency per item read or written
  • high throughput, especially when writing an incoming stream of random items
  • ability to handle datasets much larger than RAM w/o degradation
  • crash friendliness, both in terms of fast recovery and not losing data
  • ease of backup and restore
  • a relatively simple, understandable (and thus supportable) code structure and data format
  • predictable behavior under heavy access load or large volume