Thank you Rakesh. I will try it out On Thu, Nov 10, 2016 at 8:30 PM, Rakesh Radhakrishnan <[email protected]> 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 < > [email protected]> 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?. > > >
