Election Protocols

Mike Brown_3 — Fri, 29 Jun 2001 14:18:38 GMT

Can anyone tell me;
a) how the election protocol within MC/SG actually works to elect a cluster co-ordinator,
OR
b) if this info is not disclosed to the average punter like me because we don't need to know.
Thanks.

Re: Election Protocols

Carsten Krege — Sat, 30 Jun 2001 10:59:58 GMT

The election protocol is both: pretty complex and company confidential. ;) We cannot give away all the details, but it involves the following steps:

- each node starts sending UDP messages to find a coordinator
- one node becomes "candidate" and answers all incoming UDP messages and initiates heartbeat connections (hacl-hb) to the other nodes
- the other nodes become "voters", also open a heartbeat connection to the "candidate" node and send their vote
- if the candidate receives enough votes it becomes a "locker" node and "general service" (hacl-gs) connections between all nodes are setup
- When all of these messages are received (and all general service connections are ready), the candidate/locker/coordinator node enters a new state and sends a "go" message to all other nodes once they are ready
- the cluster formed

Crucial is the exact timing used for each of the steps. During election many of the various SG subsystems (package manager, network manager, SLVM etc) are reconfigured.

As I said the procedure is very complex. The algorithm has to ensure that a "split brain" (see manual) situation cannot occur at any time.

To administer a SG cluster it is not necessary to understand all the details of the election protocol though.

Carsten

Re: Election Protocols

Mike Brown_3 — Mon, 02 Jul 2001 08:46:22 GMT

Carsten - thanks for your reply. That's perfect.
Mike.

topic Election Protocols in Operating System - HP-UX

Election Protocols

Re: Election Protocols

Re: Election Protocols