title: MongoDB WiredTiger Storage Engine cacheSizeGB configure option
body: <p>What's the minimum number of cacheSizeGB can I configure which configure option introduce by MongoDB 3.0.0 in WiredTiger Storage Engine? </p>
  
  <p>Represent the number of cacheSizeGB must be integer? Can I configure it with floating number like 15.5? </p>
  
  <p>I cannot find the detail from MongoDB official document.</p>