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From Tomàs Núnez <tomas.nu...@groupalia.com>
Subject Re: any way to get the #writes/second, reads per second
Date Tue, 14 May 2013 10:53:37 GMT
Yes, there isn't any place in the JMX with reads/second or writes/second,
just CompletedTasks. I send this info to Graphite (
http://graphite.wikidot.com/) and use the "derivative" function to get
reads/minute. Munin also does the trick (https://github.com/tcurdt/jmx2munin).
But you can't do that with cassandra itself, you need somewhere to make the
calculations (cacti is also a good match).

Hope that helps. There is some more information about monitoring this kind
of things here:
http://www.tomas.cat/blog/en/monitoring-cassandra-relevant-data-should-be-watched-and-how-send-it-graphite



2013/5/13 Hiller, Dean <Dean.Hiller@nrel.gov>

> We running a pretty consistent load on our cluster and added a new node to
> a 6 node cluster Friday(QA worked great, but production not so much).  One
> mistake that was made was starting up the new node, then disabling the
> firewall :( which allowed nodes to discover it BEFORE the node bootstrapped
> itself.  We shutdown the node and booted him up and he bootstrapped himself
> streaming all the data in.
>
> After that though, all the ndoes have really really high load numbers now.
>  We are trying to figure out what is going on still.
>
> Is there any way to get the number of reads/second and writes/second
> through JMX or something?  The only way I can see of on doing this is
> manually calculating it by timing the read count and dividing by my manual
> stop watches start/stop times(timerange).
>
> Also, while my load is load average: 20.31, 19.10, 19.72 , what does a
> normal iostat look like?  My iostat await time is 13.66 ms which I think is
> kind of bad, but not that bad to cause a load of 20.31?
>
> Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s avgrq-sz
> avgqu-sz   await  svctm  %util
> sda               0.02     0.07   11.70    1.96  1353.67   702.88   150.58
>     0.19   13.66   3.61   4.93
> sdb               0.00     0.02    0.11    0.46    20.72    97.54   206.70
>     0.00    1.33   0.67   0.04
>
> Thanks,
> Dean
>



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