You can definitely do this, but your reliability will be different from what might be expected. The probability of the cluster hanging due to a failure is higher than for a single machine. The probability of data loss will be lower than for a single machine. Similarly, any maintenance that requires one of the two machines to be down will cause your cluster to hang.
Can you clarify what you mean by 2 server + 1 quorum disk? Btw... one way around the downtime during maintenance is to reconfigure the cluster on the fly to use a single server during the maintenance window. You will still have a short window of freeze because you need to take down the server that is exiting the cluster first before bouncing the other server with the new config. If your maintenance period is less than a few minutes, this isn't usually worthwhile. On Mon, Dec 6, 2010 at 7:43 AM, David Alves <[email protected]> wrote: > 1- Feasibility of a two node cluster: > Q- I know zookeeper runs over (a approx. version of) paxos > and tolerates f failures in 2f+1 nodes but would it be possible to use in a > 2 server + 1 quorum disk deployment (much like windows clusters do)? The > objective would be to use ZK both for distributed (processing nodes >2) and > single processing node (2 nodes active-passive) highly available > deployments. >
