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From aaron morton <aa...@thelastpickle.com>
Subject Re: has anyone used dynamic snitch at all
Date Mon, 11 Mar 2013 13:48:21 GMT
Check that read_repair_chance on the CF's is 0.1, not the old 1.0

Wait at least 10 minutes for the DynamicSnitch to re-calculate. 

Use the org.apache.cassandra.db:type=DynamicEndpointSnitch MBean to see what scores it has
given the nodes. 

Cheers

-----------------
Aaron Morton
Freelance Cassandra Consultant
New Zealand

@aaronmorton
http://www.thelastpickle.com

On 8/03/2013, at 11:40 AM, Edward Capriolo <edlinuxguru@gmail.com> wrote:

> dynamic_snitch=true is the default. So it is usually on "wrapping" other snitches. I
have found several scenarios where it does not work exactly as your would expect.
> 
> On Fri, Mar 8, 2013 at 2:26 PM, Hiller, Dean <Dean.Hiller@nrel.gov> wrote:
> 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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