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From Peter Schuller <>
Subject Re: Gossiper question
Date Wed, 18 May 2011 07:05:11 GMT
>   I have 9 node cluster with RF-3 and using Cassandra0.70/Hector26. Recently
> we are seeing lot of "UnavailableException" at the client side. Whenever
> this happens, I found following pattern in Cassandra node's log file at that
> given time,

UnavailableException is the expected error if an insufficient number
of nodes are up in the replicate set for the row you're
reading/writing. "Up" in this case means according to gossip (what you
see with nodetool ring).

The question is really why nodes are being marked as down and whether
it's legitimate or not. There is which may be
relevant, but simple overload is also a possible reason.

/ Peter Schuller

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