Cassandra - Why does Read/Write Latency fluctuate?
I did not fully understand the stress test was doing. It was stepping up the number of threads, hence the load was stepping up, causing the latency stepping up too.

Running with 4 threadCount
Running WRITE with 4 threads until stderr of mean &lt; 0.02

Running with 8 threadCount
Running WRITE with 8 threads until stderr of mean &lt; 0.02

Running with 16 threadCount
Running WRITE with 16 threads until stderr of mean &lt; 0.02

Running with 24 threadCount
Running WRITE with 24 threads until stderr of mean &lt; 0.02

Running with 36 threadCount
Running WRITE with 36 threads until stderr of mean &lt; 0.02

Running with 54 threadCount (08:03)
Running WRITE with 54 threads until stderr of mean &lt; 0.02

Running with 81 threadCount (08:04)
Running WRITE with 81 threads until stderr of mean &lt; 0.02

Running with 121 threadCount (08:04)
Running WRITE with 121 threads until stderr of mean &lt; 0.02

Running with 181 threadCount (08:05)
Running WRITE with 181 threads until stderr of mean &lt; 0.02

Running with 271 threadCount (08:06)
Running WRITE with 271 threads until stderr of mean &lt; 0.02

Running with 406 threadCount (08:07)
Running WRITE with 406 threads until stderr of mean &lt; 0.02

Running with 609 threadCount (08:07)
Running WRITE with 609 threads until stderr of mean &lt; 0.02

Running with 913 threadCount (08:07)
Running WRITE with 913 threads until stderr of mean &lt; 0.02




Because I repeated the test 10 times back to back, there were 10 peaks.