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From Vladimir Yudovin <>
Subject Re: Cassandra Cluster Doubts
Date Tue, 25 Apr 2017 07:53:11 GMT
Hi Luis,

I don't thinks it's possible to achieve this by custom Snitch. As far as I understand Snitch
only provides cluster topology, and connectivity is done by another component/layer. And each
cluster node should be able to connect to every other node. So I would keep with Michael's
options a) - "establish network communication forthe entire cluster" 

Best regards, Vladimir Yudovin, 

Winguzone - Cloud Cassandra Hosting

---- On Fri, 21 Apr 2017 15:42:17 -0400 Luis Miguel &lt;; wrote

Hi Michael! 


Thanks for your answer I feared that was the you know if implementing my own Snitch
would be possible to handle this situation? 


De: Michael Shuler &lt;; en nombre de Michael Shuler &lt;;

Enviado: viernes, 21 de abril de 2017 19:16:43 


Asunto: Re: Cassandra Cluster Doubts 


You have one cluster that is comprised of N nodes that may be 

distributed in racks and data centers. All the nodes of your cluster 

need to be able to communicate - they are one cluster. 


I think your options would be to a) establish network communication for 

the entire cluster, or b) set up a new cluster for DCR2 and sync data 

snapshots of Keyspace2 in some manner, or c) figure out a second cluster 

that contains the data centers that do have network connectivity and 

adjust application to query the appropriate cluster. There may be some 

other creative ideas that pop up. 



Kind regards, 



On 04/21/2017 07:26 AM, Luis Miguel wrote: 

&gt; Hello! 



&gt; I have three DC: 


&gt; DC1 -&gt; 3 nodes, Keyspace1:3 

&gt; DC2 -&gt; 3 nodes, Keyspace2:3 

&gt; DCR1 -&gt; 3 nodes, Keyspace1:2, Keyspace2:2 


&gt; now I am trying to add a new datacenter to the cluster: 


&gt; DCR2-&gt; 1 node (by now), Keyspace2:1 which network configuration can 

&gt; access to DC2 and DCR1 but it will never has access to DC1. 


&gt; when I try to start the node in DCR2, it does everything right with 

&gt; Keyspace2...but Gossips DCR1 and DC1... and crashes with 

&gt; RuntimeException because it can't move data consistently from DC1 nodes 

&gt; (obviously I don't have network connection to those nodes from this 

&gt; datacenter)... 

&gt; when I try to use -Dcassandra.consistent.rangemovement= false 

&gt; option ...It also crashes with IllegalStateException: unable to find 

&gt; sufficient sources for streaming range......etc..etc.. 


&gt; It is possible to have that kind of topology in cassandra? I mean.. Can 

&gt; I have a cluster where some datacenters will never "connect" other 

&gt; datacenters? 


&gt; Thanks in advance!!! 


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