The Freeze-Frame File System

Many applications perform real-time analysis on data streams. We argue that existing solutions are poorly matched to the need, and introduce our new Freeze-Frame File System. Freeze-Frame FS is able to accept streams of updates while satisfying "temporal reads" on demand. The system is fast and accurate: we keep all update history in a memory-mapped log, cache recently retrieved data for repeat reads, and use a hybrid of a real-time and a logical clock to respond to read requests in a manner that is both temporally precise and causally consistent. When RDMA hardware is available, the write and read throughput of a single client reaches 2.6GB/s for writes and 5GB/s for reads, close to the limit (about 6GB/s) on the RDMA hardware used in our experiments. Even without RDMA, Freeze Frame FS substantially outperforms existing options for our target settings.