Here is a pretty common use case. You have an existing file server like windows 2003 or windows 2008 in the local office. Everyone in the local office is using a network share from the file server. There are some users from the branch office that may need to access the file server share from outside through VPN as well.
There are multiple pain points that worry you at this moment.
First is you are concerned about the life of the file sever and if the server stops functioning, you need to have a quick way to continue the work.