The OpsCenter graph you're referring to basically does the following: 1. For each node, find out how much the WriteOperations attribute of the StorageProxy increased during the last minute. 2. Sum these values to get a total for the cluster. 3. Divide by 60 to get an average number of WriteOperations per second for the cluster.
On Tue, Oct 11, 2011 at 3:55 PM, aaron morton <aa...@thelastpickle.com>wrote: > Its the number of mutations, a mutation is a collection of changes for a > single row across one or more column families. > > Take a look at the nodetool cfstats, this is where I assume Ops Centre is > getting it's data from. > > Cheers > > ----------------- > Aaron Morton > Freelance Cassandra Developer > @aaronmorton > http://www.thelastpickle.com > > On 12/10/2011, at 3:44 AM, Alexandru Dan Sicoe wrote: > > Hello everyone, > I was trying to get some cluster wide statistics of the total insertions > performed in my 3 node Cassandra 0.8.6 cluster. So I wrote a nice little > program that gets the CompletedTasks attribute of > org.apache.cassandra.db:type=Commitlog from every node, sums up the values > and records them in a .csv every 10 sec or so. Everything works and I get my > stats but later I found out that I am not really sure what this measure > means. I think it is the individual column insertions performed! Am I > correct? > In the meantime I installed the trial version of the DataStax Operations > Center. The cluster wide dashboard, showing Writes performed as a function > of time, gives me much smaller values of the rates, compared to the > measurement I described before. The Datastax writes/sec are of the same > order of magnitude as the batch writes I perform on the cluster. But somehow > I cannot relate between this rate and the rate of my CompletedTasks > measurement. > > How do people usually measure insertion rates for their custers ? Per > batch, per single columns or is actual data rate more important to know? > > Cheers, > Alexandru > > > -- Tyler Hobbs Software Engineer, DataStax <http://datastax.com/> Maintainer of the pycassa <http://github.com/pycassa/pycassa> Cassandra Python client library
