cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Jacques-Henri Berthemet <jacques-henri.berthe...@genesys.com>
Subject RE: does c* 3.0 use one ring for all datacenters?
Date Wed, 11 Apr 2018 12:54:07 GMT
Maybe I misunderstood something but from what I understand, each DC have the same ring (0-100
in you example) but it's split differently between nodes in each DC. I think it's the same
principle if using vnode or not.

I think the confusion comes from the fact that the ring range is the same (0-100) but each
DC manages it differently because nodes are different.

--
Jacques-Henri Berthemet

-----Original Message-----
From: Jinhua Luo [mailto:luajit.io@gmail.com] 
Sent: Wednesday, April 11, 2018 2:26 PM
To: user@cassandra.apache.org
Subject: Re: does c* 3.0 use one ring for all datacenters?

Thanks for your reply. I also think separate rings are more reasonable.

So one ring for one dc is only for c* 1.x or 2.x without vnode?

Check these references:

https://docs.datastax.com/en/archived/cassandra/1.1/docs/initialize/token_generation.html
http://www.luketillman.com/one-token-ring-to-rule-them-all/
https://community.apigee.com/articles/13096/cassandra-token-distribution.html

Even the riak official said c* splits the ring across dc:
http://basho.com/posts/business/riak-vs-cassandra-an-updated-brief-comparison/

Why they said each dc has its own ring?


2018-04-11 19:55 GMT+08:00 Jacques-Henri Berthemet
<jacques-henri.berthemet@genesys.com>:
> Hi,
>
> Each DC has the whole ring, each DC contains a copy of the same data. When you add replication
to a new DC, all data is copied to the new DC.
>
> Within a DC, each range of token is 'owned' by a (primary) node (and replicas if you
have RF > 1). If you add/remove a node in a DC, tokens will be rearranged between all nodes
within the DC only, the other DCs won't be affected.
>
> --
> Jacques-Henri Berthemet
>
> -----Original Message-----
> From: Jinhua Luo [mailto:luajit.io@gmail.com]
> Sent: Wednesday, April 11, 2018 12:35 PM
> To: user@cassandra.apache.org
> Subject: does c* 3.0 use one ring for all datacenters?
>
> Hi All,
>
> I know it seems a stupid question, but I am really confused about the documents on the
internet related to this topic, especially it seems that it has different answers for c* with
vnodes or not.
>
> Let's assume the token range is 1-100 for the whole cluster, how does it distributed
into the datacenters? Think that the number of datacenters is dynamic in a cluster, if there
is only one ring, then the token range would change on each node when I add a new datacenter
into the cluster? Then it would involve data migration? It doesn't make sense.
>
> Looking forward to clarification for c* 3.0, thanks!
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: user-unsubscribe@cassandra.apache.org
> For additional commands, e-mail: user-help@cassandra.apache.org
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: user-unsubscribe@cassandra.apache.org
> For additional commands, e-mail: user-help@cassandra.apache.org

---------------------------------------------------------------------
To unsubscribe, e-mail: user-unsubscribe@cassandra.apache.org
For additional commands, e-mail: user-help@cassandra.apache.org

Mime
View raw message