Design for Image / Uploaded file Storage in any web app (Rails 3)

I am working on an Rails 3 application which accepts user uploaded image. Currently the images are getting stored inside the public dir of my app.

But considering a scenario where I want to upgrade my rails app to a new one, I will always have to keep this public directory same for all versions of my app in order for the DB to exactly retrieve and thus show the image. Basically the link / path to the image is stored in the DB and the actual image is getting stored inside the public dir of the app.

I have read many links to understand the way the uploaded images, etc needs to be stored and have come across 2 approaches: File System Storage VS Database Storage. Due to performance and various other reasons, I prefer the File System Storage option but I am confused as how should I design it.

Definitely storing in public folder of the app is not a good idea. I also thought of storing in another dir under my ~/webapps/ and then have my app always access this path for images. This way they both remain decoupled. But again in this approach, I have to still maintain and ensure that the web apps folder always remains fine and is backed up regularly for restoration purpose.

Can someone please suggest me and guide me the correct design approach? I am sure most of the common web apps demands images to be stored and there is some standardized way for the same.

Thanks for your help and response.