Thanks David for your explanation. What happens if autobootstrap is false in the configuration file? nodes seem to choose the correct token and balance well the cluster. In this case, how did each node to select its initial token?
Carlos Pérez Miguel 2012/1/13 David McNelis <dmcne...@gmail.com>: > 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> >> >> 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 > >
