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From Vitalii Skakun <>
Subject Re: Create a smaller cluster based on snapshost
Date Mon, 22 Jun 2015 09:43:39 GMT

I'm aware of at least 2 ways:
1. create 6 node cluster, restore snapshot to it from original cluster; and
reduce this second cluster to 3 nodes.
in this case, you should be careful in picking nodes to be decommissioned
to avoid additional rebalance of cluster and changing tokens.

2. prepare the original cluster for multi-DC configuration; add second DC
with 3 nodes.
in this case, you can also switch to vnodes in 2nd, new DC, which is good

hope this helps.

2015-06-22 6:25 GMT+03:00 John Wong <>:

> Hi.
> Supposed I have a 6-node cluster running and I want to build a 3-node
> cluster based on that 6-node cluster. What is the recommended way to
> quickly build such cluster? Each node is about 120Gb and we have RF=3. We
> are on Cassandra 1.2.19 and we are not using vnode.
> My initial research shows it can either be done with sstableloader or
> restore using snapshot and fix the token range.
> In the case of sstableloader, given it is streaming, and we are restoring
> from a live server, this seems to be a slow process if we throttle the
> traffic. Even if I take this route, do I just pick 3 node out of the 6
> nodes in any random order?
> In the case of restoring from snapshots I have restored a 6-node replica
> with just copying snapshot files (along with schema files), run nodetool
> refresh, and should be able to complete in a few hours. But now with
> smaller replica, do I again just pick snapshots from any 3 nodes? What and
> why do I need to fix token range (from what I read)?
> Any feedback is appreciated.
> Thanks.
> John


with best regards,
Vitalii Skakun

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