Can't take a write lock while out of disk space Help me please!

My C:\mongodb-win32-x86_64-2.4.6\data size is 8G. I have 95G free space of drive C. But I get this message:


  com.mongodb.WriteConcernException: { "serverUsed" : "/127.0.0.1:27017"
  , "err" : "Can't take a write lock while out of disk space" , "code" :
  14031 , "n" : 0 , "connectionId" : 10 , "ok" : 1.0}


The permissions are correct to write to data folder, because first few hours application works correctly.

What is going on?

Thanks in advance.
The problem was that I used folder as a mapped drive on Windows. 

I've replaced link to the link with absolute path on the real hdd and problem has gone.

It seems that mongo checks free drive space and compares its changes with created file size.

I don't understand the reason for downvotes...