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From Marcus Bointon <mar...@synchromedia.co.uk>
Subject Re: EC2 node adding trouble
Date Thu, 26 May 2011 13:12:52 GMT
On 24 May 2011, at 23:58, Sameer Farooqui wrote:

> So, once you know what token each of the 3 nodes should have, shut down the first two
nodes, change their tokens and add the correct token to the 3rd node (in the YAML file).

I'd like to make sure I've got the right sequence of operations for adding a node without
downtime. If I'm going from 2 to 3 nodes:

1 Calculate new initial_token values using the python script
2 Change token values in existing nodes and restart them
3 Install/configure new node
4 Insert new node's token value
5 Set new node to auto-bootstrap
6 Start cassandra on new node
7 Wait for the ring to rebalance

With token changes (using values from the python script), it's clear that all nodes will have
some data moved. Does this mean that there's a possibility of overlap between regions if token
changes are not absolutely simultaneous on all nodes? That sounds dangerous to me... Or shouldn't
token values be changed on nodes containing data?

Can cassandra nodes restart without downtime?

I'm looking at http://wiki.apache.org/cassandra/MultinodeCluster but as it says it's deliberately
simplistic.

Is there a corresponding sequence for removing nodes? I'm guessing draining is involved.

Marcus
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