A couple questions: 1. Do the log records pass through the sequencer nodes on the way to their destination, or does the writer issue a request for the sequence

A couple questions: 1. Do the log records pass through the sequencer nodes on the way to their destination, or does the writer issue a request for the sequence number and wait for a response? 2. If you're maintaining the current epoch number (and sequencer location) in Zookeeper, and a sequencer starts going up and down, you're definitely going to have problems, because nodes will get potentially stale epoch/location data from Zookeeper. Unless, that is, you have Zookeeper run a full consensus algorithm for every single query for every single record you write, which would kill performance. So as long as you're using single sequencer nodes, and dealing with replication, and doing some kind of leader election to pick a new sequencer node when one goes down, why not just run a normal consensus algorithm (like Raft) for storing records? The Raft leader node serves as the sequencer, it takes care of replication, it tolerates failures, it will be no slower than what you're doing now, and it will be way more reliable.