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From Curious Patient <mongoma...@gmail.com>
Subject Re: Question about replacing a dead node
Date Tue, 03 Jun 2014 16:53:28 GMT
>
> Thanks Mongo maven:)
> I understand why you need to to do this.

My question was more from the architecture point if view. Why doesn't
> Cassandra just redistribute the data? Is it because of the gossip protocol?


Sure.. well I've attempted to launch new nodes to redistribute the data on
a temporary basis. I can't really afford to run more than a couple nodes at
a time at the moment. As we're just beginning to develop our cassandra
based app. But when I do launch new nodes the new one doesn't seem to own
more than 1% of the ring. And nodetool repair on our keyspace still fails.
And I think that's because the dead node is still showing up in the ring.

I realize we would need to have a ring of 3 nodes for the replication
factor to set right. But we were going to worry about distributing the data
to more nodes once our application firms up and becomes more usable.

Thanks


On Tue, Jun 3, 2014 at 12:45 PM, Ipremyadav <ipremyadav@gmail.com> wrote:

> Thanks Mongo maven:)
> I understand why you need to to do this.
> My question was more from the architecture point if view. Why doesn't
> Cassandra just redistribute the data? Is it because of the gossip protocol?
>
> Thanks,
> Prem
>
> On 3 Jun 2014, at 17:35, Curious Patient <mongomaven@gmail.com> wrote:
>
> Assuming replication factor is >2, if a node dies, why does it matter? If
>> we add a new node is added, shouldn't it just take the chunk of data it
>> server as the "primary" node from the other existing nodes.
>> Why do we need to worry about replacing the dead node?
>
>
> The reason this matters is because I am unable to do a nodetool repair on
> my keyspace with the dead node still being listed in nodetool status.  It
> fails complaining that it cant't reach the dead node.
>
>
> On Tue, Jun 3, 2014 at 12:18 PM, Jeremy Jongsma <jeremy@barchart.com>
> wrote:
>
>> A dead node is still allocated key ranges, and Cassandra will wait for it
>> to come back online rather than redistributing its data. It needs to be
>> decommissioned or replaced by a new node for it to be truly dead as far as
>> the cluster is concerned.
>>
>>
>> On Tue, Jun 3, 2014 at 11:12 AM, Prem Yadav <ipremyadav@gmail.com> wrote:
>>
>>> Hi,
>>>
>>> in the last week week, we saw at least two emails about dead node
>>> replacement. Though I saw the documentation about how to do this, i am not
>>> sure I understand why this is required.
>>>
>>> Assuming replication factor is >2, if a node dies, why does it matter?
>>> If we add a new node is added, shouldn't it just take the chunk of data it
>>> server as the "primary" node from the other existing nodes.
>>> Why do we need to worry about replacing the dead node?
>>>
>>> Thanks
>>>
>>
>>
>

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