title: How to force preallocation in MongoDB
body: <p>I want to create prealloc.X files in my journal folder, there is no option to explicitly create these files, it is decided by mongo whether preallocation will be done or not.</p>
  
  <p>I used --journal option but that didin't help.</p>
  
  <p>Please suggest any way or condition where prealloc.X files can be created.</p>
  
  <p>Thanks in advance!</p>