|Google file sync between servers and follow the hits for 3rd party software.|
Google file replication service microsoft
Understand that "real time" is determined by the link between the servers.
Also understand that your requirement "change a file on one server; it will change the other server." is nearly impossible.
Normally you would have users in each location with the same file open. How does any system decide which is the one to be updated? If both are changed does the last saved overwrite the other changed document?
What you desire can be done on the database level but I have yet to see it at the file level.
Only way this can work is your two servers actually store their data on a server accessed by both. This way when you change the file its the only file being changed.