Mongo volumes strange behaviour

When I use volume in mongo docker :
-v /data:/tmp/data
there is a strange behavior.
The /data docker and /tmp/data in host works fine but
when I create file in subdirectories (/data/configdb/testfile for example) then there is no file on host . The same when I create file on host in /tmp/data/configdb)

When I create subfolder (/data/TEST) it works in docker and host.

Is it normal ??

PS , Yes, I now , I should mount the /data/db folder, byt the question is: can I mount folder with their subfolders ?

Thank you

System : debian wheezy
image: mongo