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From Alexandru Dan Sicoe <>
Subject Quick DataStax OpsCenter question
Date Thu, 17 Nov 2011 13:35:14 GMT

 I'm using the community version of OpsCenter to monitor my clutster. At
the moment I'm interested in storage space. In the performance metrics
page, if I choose to see the graph of a the metric "CF: SSTable Size" for a
certain CF of interest,  two things are plotted on the graph: Total disk
used (Total) and Live disk used (Total). Does anyone know what they mean?
And what is the difference? "Total disk used" gives me the same value as
the size on disk of the files corresponding to the CF in the data directory
(all files starting with CF name and having Statistics, Data, Filter, Index
or Compacted). But what is the "Live disk used"? I thought it is just the
raw data on disk (column names and values) without any SSTable overhead,
but this is not true because it reports a lower value than if I see the
disk usage of just the "CFName-..-Data.db" files.
 I'm always confused about what all the metrics in the OpsCenter mean and
how they are calculated. Is there a reference explaining all of them? Most
are mapped to the JMX attributes exposed...but even for those, I've never
found a reference explaining them in detail. Any suggestions?


P.S.  I'm using Cassandra 0.8.5

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