title: 7zip creates different number of files for slight difference in size
body: <p>I am using the following command:</p>
  
  <blockquote>
    <p>7z u output.7z *.bak -v250m -y</p>
  </blockquote>
  
  <p>to zip .bak (MS SQL database backup) files into 250 Mb chunks.</p>
  
  <p>For a .bak file of 7.50 GB size the command creates 8 zip chunks of 256 Mb (max). Whereas the same command creates 34 zip chunks of 256 Mb (max) when the .bak file is of 9.82 GB. The difference between these two .bak files is only around 2.3 GB but the number of zip files created is 3 times more than the other.</p>
  
  <p>Anyone any idea why that might be happening?</p>