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From Colin <>
Subject Re: How safe is "nodetool move" in 1.2 ?
Date Thu, 17 Apr 2014 00:59:05 GMT
I have recently tested this scenario under a couple versions of Cassandra and have been able
to write and read to/from the cluster while performing a move.

I performed these tests utilizing an RF=2 on a three node cluster while performing quorum
reads and received no errors due to unavailable replicas.

I will be doing some more testing on this under different scenarios, but so far so good

However, I would strongly recommend an RF of at least 3 when performing quorum based reads
because otherwise you're subject to failed reads in event of losing one node.


> On Apr 16, 2014, at 6:28 PM, Richard Low <> wrote:
>> On 16 April 2014 05:08, Jonathan Lacefield <> wrote:
>> Assuming you have enough nodes not undergoing "move" to meet your CL requirements,
then yes, your cluster will still accept reads and writes.   However, it's always good to
test this before doing it in production to ensure your cluster and app will function as designed.
> This is not a correctness requirement: writes go to the move source and destination during
the move and reads come from the source. Otherwise you could lose data during move (and certainly
would lose data if replication factor was one). However, nodes that are involved in the move
will be slower so it will be better for performance to not move nodes that share replicas
> Richard.

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