Hi Ben,

Let me clarify. Based on my observation, once a server loses touch with the 
rest of the cluster you have to rejoin it. At the same time it is not readily 
apparent that you have to do the clean up (removal) yourself. For example, you 
had a cluster of 3 nodes, then after some time one node is out. You go to that 
node and do a cluster join. My understanding is that a new server id gets 
generated.

Now, if you did not do a cleanup, you end up with 4 node cluster. When 3 out of 
4 are working, there is no issue. It is almost mandatory to do a cleanup after 
join.

Best Regards,
Paul Greenberg

________________________________
From: Ben Pfaff <b...@ovn.org>
Sent: Friday, November 2, 2018 2:30 PM
To: Paul Greenberg
Cc: Yifeng Sun; ovs dev
Subject: Re: [ovs-dev] [PATCH] ovsdb: Clarify that a server that leaves a 
cluster may never rejoin.

I'm not sure what you mean. Do you mean that the commands for removing
a server from a cluster aren't documented well enough? Or something
else?

On Thu, Nov 01, 2018 at 07:03:07PM +0000, Paul Greenberg wrote:
> I would also add that when a server leaves a cluster, it must be removed 
> using “ovs-appctl -t db.sock.ctl cluster/kick <dead-server-id>”
>
> Best Regards,
> Paul Greenberg
>
> ________________________________
> From: ovs-dev-boun...@openvswitch.org on behalf of Yifeng Sun 
> <pkusunyif...@gmail.com>
> Sent: Thursday, November 1, 2018 2:25 PM
> To: Ben Pfaff
> Cc: ovs dev
> Subject: Re: [ovs-dev] [PATCH] ovsdb: Clarify that a server that leaves a 
> cluster may never rejoin.
>
> Looks good to me, thanks.
> Reviewed-by: Yifeng Sun <pkusunyif...@gmail.com>
>
> On Mon, Oct 29, 2018 at 4:37 PM Ben Pfaff <b...@ovn.org> wrote:
>
> > This wasn't clear from the documentation.
> >
> > Reported-by; Paul Greenberg <green...@outlook.com>
> > Signed-off-by: Ben Pfaff <b...@ovn.org>
> > ---
> > Documentation/ref/ovsdb.7.rst | 3 +++
> > ovsdb/ovsdb-server.1.in | 3 +++
> > 2 files changed, 6 insertions(+)
> >
> > diff --git a/Documentation/ref/ovsdb.7.rst b/Documentation/ref/ovsdb.7.rst
> > index 39d85b6e5774..f891309fc05d 100644
> > --- a/Documentation/ref/ovsdb.7.rst
> > +++ b/Documentation/ref/ovsdb.7.rst
> > @@ -255,6 +255,9 @@ cluster: transactions not yet replicated to the server
> > will be lost, and
> > transactions not yet applied to the cluster may be committed. Afterward,
> > any
> > servers in its former cluster will regard the server to have failed.
> >
> > +Once a server leaves a cluster, it may never rejoin it. Instead, create
> > a new
> > +server and join it to the cluster.
> > +
> > The servers in a cluster synchronize data over a cluster management
> > protocol
> > that is specific to Open vSwitch; it is not the same as the OVSDB protocol
> > specified in RFC 7047. For this purpose, a server in a cluster is tied
> > to a
> > diff --git a/ovsdb/ovsdb-server.1.in b/ovsdb/ovsdb-server.1.in
> > index 2d80dafffb7d..9f78e87f655c 100644
> > --- a/ovsdb/ovsdb-server.1.in
> > +++ b/ovsdb/ovsdb-server.1.in
> > @@ -339,6 +339,9 @@ executed.
> > .IP
> > Use \fBovsdb\-client wait\fR (see \fBovsdb\-client\fR(1)) to wait
> > until the server has left the cluster.
> > +.IP
> > +Once a server leaves a cluster, it may never rejoin it. Instead,
> > +create a new server and join it to the cluster.
> > .
> > .IP "\fBcluster/kick \fIdb server\fR"
> > Start graceful removal of \fIserver\fR from \fIdb\fR's cluster, like
> > --
> > 2.16.1
> >
> > _______________________________________________
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> > d...@openvswitch.org
> > https://mail.openvswitch.org/mailman/listinfo/ovs-dev
> >
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