I am purely talking about a DR scenario. As in we can safely assume that the primary DC is no longer available. Also before the DR, the clients were connecting to the ZK ensemble in primary and after the DR they will connect to the ZK ensemble in secondary DC. You wont have a split brain problem. The only problem I see is potential loss of some data. The question really was if there are any gotchas in reconfiguring a Zookeeper node which was a observer to now be a leader/follower.
Thanks -Raj On Tue, Jul 10, 2012 at 6:31 AM, David Nickerson < [email protected]> wrote: > Hi Raj, > > I've been considering this same solution for my project. Let's say that the > secondary DC automatically makes its own quorum when it can no-longer see > the primary. Then you have a case where a network partition can result in > your quorum splitting into two autonomously running quorums. (ZooKeeper's > majority rule exists to prevent this situation.) Just make sure that you > have some additional logic that invalidates the primary once it can > no-longer be found. > > On Tue, Jul 10, 2012 at 3:39 AM, César Álvarez Núñez < > [email protected]> wrote: > > > Yes you can. Just edit the zoo.cfg from the backup DC, comment the lines > > relative to the nodes in the primary DC and the observer peer type. > > > > In this way you can start a new ZK ensemble with just the 3 servers on > > backup DC. > > > > But be aware that due to latency issues the backup DC could not have the > > latest changes from the active DC. > > > > You will also need to update each client "connection string" to use only > > the servers from the backup DC. > > > > /Sent from my GP0. > > El 09/07/2012 23:16, "Raj N" <[email protected]> escribió: > > > > > Let's say you have 2 DCs, primary and secondary. The primary DC has a 3 > > > node zookeeper quorum. And the secondary DC has 3 nodes that are > > observers. > > > Is it possible in a DR scenario(primary down) to make the 3 observer > > nodes > > > the new quorum? > > > > > > Thanks > > > -Raj > > > > > >
