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From Fabien Rousseau <fabifab...@gmail.com>
Subject Re: Streaming from 1 node only when adding a new DC
Date Tue, 14 Jun 2016 20:35:15 GMT
We've tested with C* 2.1.14 version
Yes VNodes with 256 tokens
Once all the nodes in dc2 are added, schema is modified to have RF=3 in dc1
and RF=3 in dc2.
Then on each nodes of dc2:
nodetool rebuild dc1
Le 14 juin 2016 10:39, "kurt Greaves" <kurt@instaclustr.com> a écrit :

> What version of Cassandra are you using? Also what command are you using
> to run the rebuilds? Are you using vnodes?
>
> On 13 June 2016 at 09:01, Fabien Rousseau <fabifabi95@gmail.com> wrote:
>
>> Hello,
>>
>> We've tested adding a new DC from an existing DC having 3 nodes and RF=3
>> (ie all nodes have all data).
>> During the rebuild process, only one node of the first DC streamed data
>> to the 3 nodes of the second DC.
>>
>> Our goal is to minimise the time it takes to rebuild a DC and would like
>> to be able to stream from all nodes.
>>
>> Starting C* with debug logs, it appears that all nodes, when computing
>> their "streaming plan" returns the same node for all ranges.
>> This is probably because all nodes in DC2 have the same view of the ring.
>>
>> I understand that when bootstrapping a new node, it's preferable to
>> stream from the node being replaced, but when rebuilding a new DC, it
>> should probably select sources "randomly" (rather than always selecting the
>> same source for a specific range).
>> What do you think ?
>>
>> Best Regards,
>> Fabien
>>
>
>
>
> --
> Kurt Greaves
> kurt@instaclustr.com
> www.instaclustr.com
>

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