I one website that runing with two nameservers ns1 and ns2. For example if the current website is hosted on ns1 and I upload serveral files on ns1. If ns1 is down, and ns2 takes over. How can ns2 get all the file that I previously uploaded in ns1.
Not all sites run off of two name servers. In all reality, name servers should be seperate physical (worst case, logical) machines. You may be uploading to the same server which acts as a nameserver, but that's.... well, enough said.
I think you should better explain your question so we can answer it better.