ah okay,
we dont know our capacity yet.
We need a solution which is highly and automatically scalable to solve our issues

What configuration of Storage Server do you plan.

How many HDD and what storage and network capacity ?

I plan also bulit huge OSSN site with cluster topology so we are solving similar problem.

I would like test as databse server open source distibuted database TiDB insteda of MySQL. TiDB is in strong development in China and is in beta release now. Hope it will works soon.

Yes. I not tested this solution but theoreticaly it should works.

ah okay that would be an interesting solution. so we would have ossn and ossndata on the server but ossndat is mapped with NFS to storage server so both ossn_data are mapped to storage

I think that what is only needed is to map ossn_data folder on both applications servers to storage server file system via NFS.

I think there is no need any script.

There should be definetly a way to achieve this.
Otherwise you have to write a php script or something like this to upload it to storage server and move manually. Then you have you modify the Core (hope there is hook or so) to change the loaded image source

Yes, I am interesting also if this configuration works.

I think it is possible to config 2 application servers to map with NFS to one Storage Servere.