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From Sergey Naumov <sknau...@gmail.com>
Subject Re: How to add new DC to cluster when GossipingPropertyFileSnitch is used
Date Fri, 17 May 2013 08:19:29 GMT
But I've read in some sources (for example
http://www.datastax.com/docs/1.0/initialize/cluster_init_multi_dc) that
seed list MUST include at least one seed from each DC and seed lists should
be the same for each node.

Or it is fine if nodes from new DC have all seeds specified and nodes from
old DCs have all seeds specified except seeds from new DC? In such
interpretation rules have to be a bit modified:
1. Nodes from the same DC should have identical seeds lists.
2. At least at one DC nodes MUST have in its seed lists seeds from all
other DCs.


2013/5/17 Igor <igor@4friends.od.ua>

>  I see no reason to restart all nodes. You can continue to use seed from
> first DC - seed used for loading ring configuration(locations, token
> ranges, etc), not data.
>
> On 05/17/2013 10:34 AM, Sergey Naumov wrote:
>
>  If I understand you correctly, GossipingPropertyFileSnitch is useful for
> manipulations with nodes within a single DC, but to add a new DC without
> having to restart every node in all DCs (because seeds are specified in
> cassandra.yaml and I need to restart a node after addition of a new seed
> from newly created DC), I anyway have to use cassandra-topology.properties
> and edit it on every node of a cluster.
>
>  By the way, it it necessary to specify seeds if I use PropertyFileSnitch
> and there is info in cassandra-topology.properties about all nodes of a
> cluster?
>
>
> Yes, it is. Cassandra need seed(s), because topology properties have no
> info about token ranges.
>
>
>
> 2013/5/17 aaron morton <aaron@thelastpickle.com>
>
>> You should configure the seeds as recommended regardless of the snitch
>> used.
>>
>> You need to update the yaml file to start using the
>> GossipingPropertyFileSnitch but after that it reads the
>> cassandra-rackdc.properties file to get information about the node. It
>> reads uses the information in gossip to get information about the other
>> nodes in the cluster.
>>
>> If there is no info in gossip about a remote node, because say it has not
>> been upgraded, it will fall back to using cassandra-topology.properties.
>>
>> Hope that helps.
>>
>> -----------------
>> Aaron Morton
>> Freelance Cassandra Consultant
>> New Zealand
>>
>> @aaronmorton
>> http://www.thelastpickle.com
>>
>> On 15/05/2013, at 8:10 PM, Sergey Naumov <sknaumov@gmail.com> wrote:
>>
>> > As far as I understand, GossipingPropertyFileSnitch supposed to provide
>> more flexibility in nodes addition/removal. But what about addition of a
>> DC? In datastax documentation (
>> http://www.datastax.com/docs/1.2/operations/add_replace_nodes#add-dc) it
>> is said that cassandra-topology.properties could be updated without restart
>> for PropertyFileSnitch. But here (
>> http://www.datastax.com/docs/1.0/initialize/cluster_init_multi_dc) it it
>> said, that "you MUST include at least one node from EACH data center. It is
>> a best practice to have at more than one seed node per data center and the
>> seed list should be the same for each node". At the first glance it seems
>> that PropertyFileSnitch will get necessary info from
>> cassandra-topology.properties, but for GossipingPropertyFileSnitch
>> modification of cassandra.yaml and restart of all nodes in all DCs will be
>> required. Could somebody clarify this topic?
>> >
>> > Thanks in advance,
>> > Sergey Naumov.
>>
>>
>
>

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