Koert, I think this is a more appropriate question for the HBase mailing list. HBase uses ZooKeeper for Master failover. It is possible that if the Master is down and namenode/others are up, HBase can failiover to the new master. You have a good point of having ZK running on Master/NN/SNN, so you'd have to avoid running ZK on those machines. Hope that helps.
mahadev On Fri, Nov 11, 2011 at 7:15 AM, Koert Kuipers <[email protected]> wrote: > in various places i have read that in production one should really have a > zookeeper ensemble (with an odd number of members) as opposed to a single > zookeeper. this was also mentioned for example in the base documentation. > however, if your cluster has a single machine with namenode, secondary > namenode and hbase master, what is the benefit of having a zookeeper > cluster? if that one machine goes down your hbase isn't doing anything > anyhow, so why even bother running a zookeeper ensemble in this case? why > not just use a single zookeeper? > > are the performance benefits a reason to run a zookeeper ensemble even in > this scenario? (faster reads perhaps) >
