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From Fabien Rousseau <>
Subject Streaming from 1 node only when adding a new DC
Date Mon, 13 Jun 2016 09:01:51 GMT

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,

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