Yes, I thought about Cassandra or Voldemort, but I need ZKs guarantees as it will provide the file system hierarchy to a flat object store so I need locking primitives and consistency. Doing that on top of Voldemort will give me a scalable version of ZK, but just slower. Might as well find a way to scale across ZK clusters.

Also, I want to be able to add clusters as the number of nodes grows. Note that the #nodes will grow with the #users of the system, so the clusters can grow sequentially, hence the symlink idea.


On 07/24/2010 11:12 PM, Ted Dunning wrote:
Depending on your application, it might be good to simply hash the node name
to decide which ZK cluster to put it on.

Also, a scalable key value store like Voldemort or Cassandra might be more
appropriate for your application.  Unless you need the hard-core guarantees
of ZK, they can be better for large scale storage.

On Sat, Jul 24, 2010 at 7:30 AM, Maarten Koopmans<>wrote:


I have a number of nodes that will grow larger than one cluster can hold,
so I am looking for a way to efficiently stack clusters. One way is to have
a zookeeper node "symlink" to another cluster.

Has anybody ever done that and some tips, or alternative approaches?
Currently I use Scala, and traverse zookeeper trees by proper tail
recursion, so adapting the tail recursion to process "symlinks" would be my

Bst, Maarten

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