title: MongoDB - difference between mongo.log files and journal log files
body: <p>While using mongo, I got huge log files (several Gs) under my /var/log/mongodb directory.
  Example:</p>
  
  <pre><code>root@redis-frankfurt-production:/var/log/mongodb# ls -ltrh /var/log/mongodb/mongod.log*
  -rw-r--r-- 1 root root 9.2G Aug 29 06:10 /var/log/mongodb/mongod.log.2016-08-29T10-29-04
  -rw-r--r-- 1 root root 2.5G Aug 29 10:01 /var/log/mongodb/mongod.log.2016-08-29T14-03-30
  </code></pre>
  
  <p>In addition, there are the journal logs:</p>
  
  <pre><code>root@redis-frankfurt-production:/var/log/mongodb# ls -ltrh /var/log/mongodb/journal/
  total 301M
  -rw-r--r-- 1 mongodb mongodb 101M Jun 17 13:10 WiredTigerPreplog.0000000002
  -rw-r--r-- 1 mongodb mongodb 101M Jun 17 13:10 WiredTigerPreplog.0000000001
  -rw-r--r-- 1 mongodb mongodb 101M Jun 17 13:10 WiredTigerLog.0000000001
  </code></pre>
  
  <p>From what I understood the journal logs are used to sync between memory levels.
  And the logs which are under /var/log/mongodb/mongod.log.* are pure logging data.
  From what I see, the dates of the logs are not changing over time (last modified date).</p>
  
  <p>Here is my question:
  Is it possible to delete old /var/log/mongodb/mongod.log.* (not touching the journal logs)?</p>
  
  <p>Thanks!</p>