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From Jai Bheemsen Rao Dhanwada <jaibheem...@gmail.com>
Subject Re: Zookeeper upgrade
Date Fri, 11 Nov 2016 16:49:23 GMT
Thank you Rakesh.
I will try it out

On Thu, Nov 10, 2016 at 8:30 PM, Rakesh Radhakrishnan <rakeshr@apache.org>
wrote:

> Probably you could do rolling restarts. You have to do this manually by,
>
>
> Pre-requisite:- Ensure all the servers in the cluster is running. For
> example, if you have three node cluster A, B and C. Assume, A & B are
> Followers and C is the Leader. This is to ensure that, if one of the server
> stopped(assume A) during upgrade step then other servers(B & C) would be
> able to provide service to the ZooKeeper clients.
>
> step-1) stop one server at a time,
> step-2) then upgrade new software,
> step-3) finally restart the server back.
> The upgrade is now complete on this server and you can proceed to the next.
>
> Now, the restarted server will join the quorum. The side effect of this is,
> since this server is getting stopped all the clients(sessions) connected to
> this server will be Disconnected and then Reconnected with other server in
> the ZK cluster.
>
> When you do the above steps in LEADER server, then surely the quorum will
> be lost and all the other running PARTICIPANTS will enter into quorum
> reformation phase and elect one among them as new LEADER. Here also, you
> will see all the clients(sessions) connected to this cluster will be
> Disconnected and then Reconnected back safely. AFAIK, two times clients
> will get Disconnected and then Reconnected events, if you have watcher
> registered.
>
> I'd prefer to start rolling upgrade from OBSERVERs, then FOLLOWERs and at
> the end will pick the LEADER server. This way you could get chance to
> monitor your newly upgraded server for any inconsistencies with less client
> Disconnections. Perhaps, do rolling back if any issues are encountered.
>
> Imp Note*:*- I hope you will first experiment rolling upgrade steps in your
> test cluster and then do it in production cluster.
>
> References:-
> https://wiki.apache.org/hadoop/ZooKeeper/FAQ#A6
> https://www.cloudera.com/documentation/enterprise/5-5-
> x/topics/cdh_ig_zookeeper_earlier_cdh5_upgrade.html
>
> Thanks,
> Rakesh
>
> On Fri, Nov 11, 2016 at 9:22 AM, Jai Bheemsen Rao Dhanwada <
> jaibheemsen@gmail.com> wrote:
>
> > Hello All,
> >
> > I am using zookeeper 3.4.5 version in production and would like to
> upgrade
> > to the latest version 3.4.9
> >
> > Can someone point me to the correct upgrade(with out having a downtime)
> > path?.
> >
>

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