title: Commitlog incremental switch
body: <p>We get a burst of  'No segments I reserve; creating a new  one'in log,as soon as we start our performance  burst run on a single node cassandra Cluster.<br>
  Presumably, this means the commit log is expanding to grab more segments;which would impact the performance metrics.<br>
  Questions on the above:  </p>
  
  <pre><code>1.Can this be avoided by pre-reserving segments for commit log and how.  
  2.How can we query the current limit of a commitlog for a cassandra instace.  
  3.We also notice memtable flush pointing to commitlog activity. Does commitlog sync duration  trigger table flushes  
  </code></pre>
  
  <p>We are using version 3.11.x</p>