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From Jonathan Ellis <>
Subject Re: Cassandra Health Monitoring
Date Sun, 27 Jun 2010 17:53:41 GMT
short version:

if o.a.c.concurrent.{ROW-READ-STAGE,ROW-MUTATION-STAGE} and
o.a.c.db.CompactionManager have

 - completed task count increasing
 - pending tasks stable (for RRS and RMS, stable in low hundreds or
less, for CM stable in single digits or less)
 - the log isn't spitting out Error lines

then the node is completing requests and keeping up with demand reasonably well.

On Tue, Jun 22, 2010 at 3:41 PM, Andrew Psaltis
<> wrote:
> All,
> We have been working through some operations scenarios, so that we are ready to deploy
our first Cassandra cluster into production  in the coming months. During this process our
operations folks have asked us to provide a Health Check service. I am using the word service
here very liberally - really we just need to provide a way for the folks in out NOC to know
that not only is the Cassandra process running (which they will get with their monitoring
tools ), but that it is actually alive and well. We do not have the intent of verifying that
the data is valid, just that every node in the cluster that is known to be running is actually
alive and healthy. My questions are - What does it mean for a Cassandra node to be healthy?
 What is the minimum (from an impact to the performance of a node) things we can check to
make sure that a node is not a zombie?
> Any and all input is greatly appreciated.
> Thanks,
> Andrew

Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support

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