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From abhinav prakash rai <>
Subject Re: performance degradation in cluster
Date Thu, 03 Feb 2011 09:22:35 GMT
Hi Peter,

Thanks for your reply.

Our application is multi-threaded. we are using 8 core machine. In our
application we are using 4 column families out of which one column family is
containing rows whose size is huge relative to size of the rows in other
column families.

In the ring the balance is highly skewed.Can you suggest we can insure even
balancing of the load across the cluster?

The rows id in one column family is combination of cell numbers ( ie
9883240354_9885430354 ) and other row id's are like thread_name_12234 etc.

How to insure spreading the data across rows?

Thanks & Regards,

On Thu, Feb 3, 2011 at 1:46 PM, Peter Schuller

> > First time I tun single instance of Cassandra and my application on a
> system
> > (16GB ram and 8 core), the time taken was 480sec.
> > When I added one more system ,(means this time I was running 2 instance
> > of Cassandra in cluster) and running application from single client , I
> > found time taken in increased to 1000sec.   And I also found that that
> data
> > distribution was also very odd on both system (in one system data were
> about
> > 2.5GB and another were 140MB).
> > Is any configuration require while running Cassandra in a cluster other
> than
> > adding seeds ?
> For starters:
> (1) Are you spreading your data around evenly across row? Rows
> determine where data is placed in the cluster.
> (2) Is your ring actually balanced? (nodetool ring, they should have 50/50)
> (3) Is your test concurrent/multi-threaded? Increasing total time
> would be expected if you're moving from local traffic only to running
> against remote machines,  if your test is a sequential workload.
> Adding machines increases aggregate throughput across multiple
> clients; it won't make individual requests faster (except indirectly
> of course by avoiding overloaded conditions).
> --
> / Peter Schuller

Abhinav P. Rai

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