[PATCH] Do not allow different versions of ctdb in a cluster

[Amitay Isaacs]

On Tue, May 23, 2017 at 4:48 PM, Stefan Metzmacher <metze at samba.org> wrote:

> Hi Amitay,
>
> I guess there's no way to detect the version mismatch at the
> "connect" time? Or is the keepalive message the first message
> that's send over the connection?
>
> metze
>
>
As soon as ctdb daemon starts up, it starts sending keepalive messages to
the connected nodes every 5 seconds.  So strictly keepalive may not be the
very first message sent to the other node, but keepalive messages will
definitely be acted upon before the first recovery happens.  That is good
enough for shutting down the node in case of version mismatch.

This is the smallest change I could think of to enable version checking
without breaking backward compatibility for protocol.

In future, cluster daemon will implement the version check as part of the
election process.  These will be the very first messages sent between the
nodes.

Amitay.