> Does snapshotting means dumping snap data on memory into disk? Yes.
> Small snapCount would take little time for snapshotting, it means shorter > stopping world. Do I understand properly? The amount of time it takes to take a snapshot is proportional to the amount of data stored in ZooKeeper. Taking snapshots more frequently doesn't reduce the snapshot time. ZooKeeper takes what's called 'fuzzy snapshots' and it doesn't block writes (i.e. stop the world) during the snapshot. ZooKeeper recovers to a consistent state by loading the fuzzy snapshot and replaying all the transactions since the snapshot process started. This works because all the ZooKeeper operations are idempotent.
