Hi Mahadev, It lets one run multiple 2-node clusters. Suppose I have an application that does a simple 2-way mirroring of my data and uses ZK for clustering. If I need to support many 2-node clusters, where will I find the spare machines to run the third instance for each cluster?
-Vishal On Mon, Oct 25, 2010 at 5:14 PM, Mahadev Konar <maha...@yahoo-inc.com>wrote: > Hi Vishal, > This idea (2.) had been kicked around intially by Flavio. I think he¹ll > probably chip in on the discussion. I am just curious on the whats the idea > behind your proposal? Is this to provide some kind of failure gaurantees > between a 2 node and 3 node cluster? > > Thanks > mahadev > > On 10/25/10 1:05 PM, "Vishal K" <vishalm...@gmail.com> wrote: > > > Hi All, > > > > I am thinking about the choices one would have to support multiple 2-node > > clusters. Assume that for some reason one needs to support multiple > 2-node > > clusters. > > This would mean they will have to figure out a way to run a third > instance > > of ZK server for each cluster somewhere to ensure that a ZK cluster is > > available after a failure. > > > > This works well if we have to run one or two 2-node clusters. However, > what > > if we have to run many 2-node clusters? > > > > I have following options: > > 1. Find m machines to run the third instance of each cluster. Run n/m > > instances of ZK on each machine. > > 2. Modify ZooKeeper server to participate in multiple clusters. This will > > allow us to run y instances of third node where each instance will be > part > > of n/y clusters. > > 3. Run the third instance of ZK server required for the ith cluster on > one > > of the server on (i+1)%n cluster. Essentially, distribute the third > instance > > across the other clusters. > > > > The pros and cons of each approach are fairly obvious. While I prefer the > > third approach, I would like to check what everyone thinks about the > second > > approach. > > > > Thanks. > > -Vishal > > > >