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From arun sirimalla <arunsi...@gmail.com>
Subject Re: Best Practice to add a node in a Cluster
Date Tue, 28 Apr 2015 04:14:21 GMT
Hi Neha,


After you add the node to the cluster, run nodetool cleanup on all nodes.
Next running repair on each node will replicate the data. Make sure you run
the repair on one node at a time, because repair is an expensive process
(Utilizes high CPU).




On Mon, Apr 27, 2015 at 8:36 PM, Neha Trivedi <nehajtrivedi@gmail.com>
wrote:

> Thanks Eric and Matt :) !!
>
> Yes the purpose is to improve reliability.
> Right now, from our driver we are querying using degradePolicy for
> reliability.
>
>
>
> *For changing the keyspace for RF=3, the procedure is as under:*
> 1. Add a new node to the cluster (new node is not in seed list)
>
> 2. ALTER KEYSPACE system_auth WITH REPLICATION =
>   {'class' : 'NetworkTopologyStrategy', 'dc1' : 3};
>
>
>    1. On each affected node, run nodetool repair
>    <http://docs.datastax.com/en/cassandra/1.2/cassandra/tools/toolsNodetool_r.html>.
>
>    2. Wait until repair completes on a node, then move to the next node.
>
>
> Any other things to take care?
>
> Thanks
> Regards
> neha
>
>
> On Mon, Apr 27, 2015 at 9:45 PM, Eric Stevens <mightye@gmail.com> wrote:
>
>> It depends on why you're adding a new node.  If you're running out of
>> disk space or IO capacity in your 2 node cluster, then changing RF to 3
>> will not improve either condition - you'd still be writing all data to all
>> three nodes.
>>
>> However if you're looking to improve reliability, a 2 node RF=2 cluster
>> cannot have either node offline without losing quorum, while a 3 node RF=3
>> cluster can have one node offline and still be able to achieve quorum.
>> RF=3 is a common replication factor because of this characteristic.
>>
>> Make sure your new node is not in its own seeds list, or it will not
>> bootstrap (it will come online immediately and start serving requests).
>>
>> On Mon, Apr 27, 2015 at 8:46 AM, Neha Trivedi <nehajtrivedi@gmail.com>
>> wrote:
>>
>>> Hi
>>> We have a 2 Cluster Node with RF=2. We are planing to add a new node.
>>>
>>> Should we change RF to 3 in the schema?
>>> OR Just added a new node with the same RF=2?
>>>
>>> Any other Best Practice that we need to take care?
>>>
>>> Thanks
>>> regards
>>> Neha
>>>
>>>
>>
>


-- 
Arun
Senior Hadoop/Cassandra Engineer
Cloudwick

Champion of Big Data (Cloudera)
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