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From "Hiller, Dean" <Dean.Hil...@nrel.gov>
Subject has anyone used dynamic snitch at all
Date Fri, 08 Mar 2013 19:26:54 GMT
Our test setup

4 nodes, RF=3, reads at CL=QUOROM and we tried CL=TWO
Tell the network card to slow down every packet on node 2
After fixing astyanax to not go to node 2 anymore, we are still seeing cassandra have issues
as it seems to be involving node 2 somehow.  If we take node 2 down, it all speeds back up.

We are trying to get this working such that a slow node in cassandra does not impact our customers.

We are in 1.2.2 and added the following properties….(our properties show PropertyFileSnitch
though I see the keyspace has org.apache.cassandra.locator.SimpleStrategy set probably because
it was created through a tool instead of CLI…shucks)….anyways, I still expected dynamic
snitch to work….

# controls how often to perform the more expensive part of host score
# calculation
dynamic_snitch: true
dynamic_snitch_update_interval_in_ms: 100
# controls how often to reset all host scores, allowing a bad host to
# possibly recover
dynamic_snitch_reset_interval_in_ms: 600000
# if set greater than zero and read_repair_chance is < 1.0, this will allow
# 'pinning' of replicas to hosts in order to increase cache capacity.
# The badness threshold will control how much worse the pinned host has to be
# before the dynamic snitch will prefer other replicas over it.  This is
# expressed as a double which represents a percentage.  Thus, a value of
# 0.2 means Cassandra would continue to prefer the static snitch values
# until the pinned host was 20% worse than the fastest.
dynamic_snitch_badness_threshold: 0.1

Any help appreciated,
Thanks,
Dean

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