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From David McNelis <>
Subject Re: About initial token, autobootstraping and load balance
Date Fri, 13 Jan 2012 19:10:08 GMT
The documentation for that section needs to be updated...

What happens is that if you just autobootstrap without setting a token it
will by default bisect the range of the largest node.

So if you go through several iterations of adding nodes, then this is what
you would see:

Gen 1:
Node A:  100% of tokens, token range 1-10 (for example)

Gen 2:
Node A: 50% of tokens  (1-5)
Node B: 50% of tokens (6-10)

Gen 3:
Node A: 25% of tokens (1-2.5)
Node B: 50% of tokens (6-10)
Node C: 25% of tokens (2.6-5)

In reality, what you'd want in gen 3 is every node to be 33%, but it would
not be the case without setting the tokens to begin with.

You'll notice that there are a couple of scripts available to generate a
list of  initial tokens for your particular cluster size, then ever time
you add a node you'll need to update all the nodes with new tokens in order
to properly load balance.

Does this make sense?

Other folks, am I explaining this correctly?


2012/1/13 Carlos Pérez Miguel <>

> Hello,
> I have a doubt about how initial token is determined. In Cassandra's
> documentation it is said that it is better to manually configure the
> initial token to each node in the system but also is said that if
> initial token is not defined and autobootstrap is true, new nodes
> choose initial token in order to better the load balance of the
> cluster. But what happens if no initial token is chosen and
> autobootstrap is not activated? How each node selects its initial
> token to balance the ring?
> I ask this because I am making tests with a 20 nodes cassandra cluster
> with cassandra 0.7.9. Any node has initial token, nor
> autobootstraping. I restart the cluster with each test I want to make
> and in the end the cluster is always well balanced.
> Thanks
> Carlos Pérez Miguel

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