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From Peter Schuller <>
Subject Re: Stuck with adding nodes
Date Thu, 09 Dec 2010 19:25:11 GMT
> Currently I am copying all data files (thats all existing data) from one node to the new
nodes in hope that I could than manually assign them their new tokenrange (nodetool move)
and do cleanup.

Unless I'm misunderstanding you I believe you should be setting the
initial token. nodetool move would be for a node already in the ring.
And keep in mind that a nodetool move is currently a
decommission+bootstrap - so if you're teetering on the edge of
overload you will want to keep that in mind when moving a node to
avoid ending up in a worse situation as another node temporarily
receives more load than usual as a result of increased ring ownership.

> Obviously I will try this tomorrow (it's been a long day) on a test system but any advice
would be highly appreciated.

One possibility if you have additional hardware to spare temporarily,
is to add more nodes than you actually need and then, once you are
significantly over capacity, you have the flexibility to move nodes
around to an optimum position and then decommission those machines
that were only "borrowed". I.e., initial bootstrap of nodes takes a
shorter amount of time because you're giving them less token space per
new node. And once all are in the ring, you're free to move things
around and then free up the hardware.

(Another option may be to implement throttling of the anti-compaction
so that it runs very slowly during peak hours, but that requires
patching cassandra or else firewall/packet filtering fu and is
probably likely to be more risky than it's worth.)

/ Peter Schuller

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