下面是bitcask的论文里，作者考虑到的目标
• 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
• a license that allowed for easy default use in Riak