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From "Jonathan Ellis (Commented) (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-3640) Dynamic Snitch does not compute scores if no direct reads hit the node.
Date Thu, 15 Dec 2011 19:20:30 GMT


Jonathan Ellis commented on CASSANDRA-3640:

I think I misunderstood on irc.  The dynamic snitch is populated based on client requests,
so it's normal for that to be empty here.  It sounds like the real question is, "were other
nodes directing requests away from the poorly performing ones, and if not, what did their
dsnitch contents look like?"
> Dynamic Snitch does not compute scores if no direct reads hit the node.
> -----------------------------------------------------------------------
>                 Key: CASSANDRA-3640
>                 URL:
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Edward Capriolo
>            Priority: Minor
> We can into an interesting situation. We added 2 nodes to our cluster. Strangely this
node performed worse then other nodes. It had more IOwait for example. The impact was not
major but it was noticeable. Later I determined that this Cassandra node was not in our client's
list of nodes and our clients do not auto discover. I confirmed that the host did not have
any scores inside it's dynamic snitch.
> It is counter intuitive that a node receiving less or no direct user requests would perform
worse then others. I am not sure of the dynamic that caused this. 
> I understand that DSnitch is supposed to have it's own view of the world, maybe it could
share information with neighbours. Again this is more of a client configuration issue then
a direct Cassandra issue, but I found it quite interesting.

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