A YAML config file containing the following info is not accepted by the server.
The documentation online says the value should be an int. However starting the server with this config file throws the error
2014-07-13T23:55:33.896+0530 SEVERE: Failed global initialization: BadValue operationProfiling.mode must be a string of the format: (off/slowOp/all)
Modifying the config file to read
fixes the issue.