systemLog:
   destination: file
   path: "/var/log/mongodb/mongod.log"
   quiet: true
   logAppend: true
storage:
   dbPath: "/data/db"
   directoryPerDB: true
   journal:
      enabled: true
   smallFiles: true
processManagement:
   fork: true
   pidFilePath: "/usr/lib/mongodb/mongod.pid"
net:
   #bindIp: 127.0.0.1
   port: XXXX
   http:
      enabled: false
replication:
 replSetName: "rs1"
 oplogSizeMB: 100
security:
  keyFile: "/usr/lib/mongodb/keyFile/secretKey.key"
  authorization: enabled

mongod --config /usr/lib/mongodb/conf/rs_member.conf
2016-01-06T04:59:49.227-0600 W CONTROL  Option: storage.smallFiles is deprecated. Please use storage.mmapv1.smallFiles instead.
about to fork child process, waiting until server is ready for connections.
forked process: 27368
ERROR: child process failed, exited with error number 100

2016-01-06T04:59:49.270-0600 I STORAGE  [initandlisten] exception in initAndListen: 72 Requested option conflicts with current storage engine option for directoryPerDB; you requested true but the current server storage is already set to false and cannot be changed, terminating
2016-01-06T04:59:49.270-0600 I CONTROL  [initandlisten] dbexit:  rc: 100
2016-01-06T05:08:22.011-0600 I CONTROL  ***** SERVER RESTARTED *****