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Posted to user@cassandra.apache.org by buddhasystem <po...@bnl.gov> on 2011/01/27 02:14:17 UTC
Why does cassandra stream data when moving tokens?
Sorry if this sounds silly, but I can't get my brain around this one: if all
nodes contain replicas, why does the cluster stream data every time I more
or remove a token? If the data is already there, what needs to be streamed?
Thanks
Maxim
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Re: Why does cassandra stream data when moving tokens?
Posted by Robert Coli <rc...@digg.com>.
On Thu, Jan 27, 2011 at 2:05 AM, aaron morton <aa...@thelastpickle.com> wrote:
> It will help if you can include the output from some of the tools, e.g.
>
> nodetool ring
> nodetool netstats
It will also help if you include the version of cassandra you are running.
=Rob
Re: Why does cassandra stream data when moving tokens?
Posted by aaron morton <aa...@thelastpickle.com>.
It will help if you can include the output from some of the tools, e.g.
nodetool ring
nodetool netstats
Aaron
On 27 Jan 2011, at 16:17, buddhasystem wrote:
>
> Removetoken command just never returns. There is nothing streaming in the
> cluster.
>
> Anyone knows what might be happening?
>
> nodetool ring returns different results on two nodes compared to the third
> one (which is the first in the ring). Weirdness started when I did move 0 on
> the no-defunct node which used to be the first. It died and when I tried to
> rebalance, I got into this inconsistency situation.
>
>
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RE: Why does cassandra stream data when moving tokens?
Posted by buddhasystem <po...@bnl.gov>.
Removetoken command just never returns. There is nothing streaming in the
cluster.
Anyone knows what might be happening?
nodetool ring returns different results on two nodes compared to the third
one (which is the first in the ring). Weirdness started when I did move 0 on
the no-defunct node which used to be the first. It died and when I tried to
rebalance, I got into this inconsistency situation.
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RE: Why does cassandra stream data when moving tokens?
Posted by buddhasystem <po...@bnl.gov>.
Thanks, I'll look at the configuration again.
In the meantime, I can't "move" the first node in the ring (after I removed
the previous node's token) -- it throws an exception and says data is being
streamed to it -- however, this is not what netstats says! Weirdness
continues...
Maxim
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RE: Why does cassandra stream data when moving tokens?
Posted by "Sadasivam, Srinivasan" <sr...@qualcomm.com>.
Not all nodes have replicas. First of all, the number of replicas is determined by replication_factor which you set when creating the keyspace - and where they go is determined by replica_placement_strategy. Say, if you pick 3, the first copy of your item are placed based on token value of the node and other two replicas on nodes based on replica_placement_strategy. So when you add a node (thus its token) and decommission a node, it causes rebalance of the data thus streaming. Hope this helps.
-----Original Message-----
From: buddhasystem [mailto:potekhin@bnl.gov]
Sent: Wednesday, January 26, 2011 5:14 PM
To: cassandra-user@incubator.apache.org
Subject: Why does cassandra stream data when moving tokens?
Sorry if this sounds silly, but I can't get my brain around this one: if all
nodes contain replicas, why does the cluster stream data every time I more
or remove a token? If the data is already there, what needs to be streamed?
Thanks
Maxim
--
View this message in context: http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Why-does-cassandra-stream-data-when-moving-tokens-tp5964839p5964839.html
Sent from the cassandra-user@incubator.apache.org mailing list archive at Nabble.com.