4 ms·
So you are saying that you have seen AOF fail multiple times to create a durable record, or fail in an adverse event to persist everything?
by ilaksh 5y ago
So you are saying that you have seen AOF fail multiple times to create a durable record, or fail in an adverse event to persist everything?
- avidiax 5y agoFsync ≠ bytes safe, unfortunately. It usually means that the bytes are in the drive's cache, not that it's on disk. In theory, the disk can write the cache if the power is cut. Even then, the disk can fail. The safe thing is a shared-nothing replica, but you need 2 of them to have availability. 3 if you are worried about bit-flips causing your 2 replicas to disagree.
- ilaksh 5y agoDoes redis not have replicas?
- avidiax 5y agoIt does. The distinction I'm making is that fsync is only 100% safe if you use it with a shared-nothing replica and min-replicas-to-write >= 2. If you have such a replica, you no longer need the fsync, and you are safe against anything but a regional-scale catastrophe.