Election vs consensus

Roberto Ostinelli ostinelli@REDACTED
Fri Jan 7 23:57:15 CET 2022

Thank you Anthony. I need to spend more time on the raft.pdf (I’ve only skimmed through it before).

Raft, afaik, once a leader is elected all it does is to send a new log (i.e. a write in a kv store) to all the followers and wait for their ack. What I’m trying to understand is what raft (a consensus algorithm) offers on top of a simple bully (a leader algorithm) with a similar ack mechanism, for example, in the context of a kv store. Some explanations probably are in the raft.pdf so that could be a good start. Thank you.

Any other pointers welcome!


> On 7 Jan 2022, at 23:24, Anthony Howe <achowe@REDACTED> wrote:
> On 2022-01-07 17:14, Roberto Ostinelli wrote:
>> Dear list,
>> This is not directly related to erlang but for obvious reasons it’s pretty tightly related. 
>> I would like to understand why election algorithms such as bully are afaik deemed not enough to build consistent systems, hence the existence of consensus algorithms such as paxos/raft. More specifically in the creation of simple key/value stores.
>> I would have imagined that with leader election you can pipe all the read/write operations through the leader, hence implement consistency. However i.e. raft came in to fill this kind of scenario, and I would like to understand why it is needed. 
>> Does someone have pointers on things to read?
> Some of the Leader Election / RAFT related material I collected when I was
> looking into the subject.
> https://raft.github.io/raft.pdf
> https://www.elastic.co/blog/found-leader-election-in-general
> https://www.tigera.io/blog/using-etcd-for-elections/
> -- 
> Anthony C Howe                                                    SnertSoft
> achowe@REDACTED     Twitter: SirWumpus            BarricadeMX & Milters
> http://snert.com/    http://nanozen.snert.com/     http://snertsoft.com/

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