I'm just wondering -- what's wrong with manual specification of tokens?
I'm so glad I did it and have not had problems with balancing and all.
Before I was indeed stuck with 25/25/50 setup in a 3 machine cluster,
when had to move tokens to make it 33/33/33 and I screwed up a little in
that the first one did not start with 0, which is not a good idea.
Maxim
On 1/13/2012 2:10 PM, David McNelis wrote:
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?
David
2012/1/13 Carlos Pérez Miguel <cperez...@gmail.com
<mailto:cperez...@gmail.com>>
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
