Auto save server architecture

I want to save a lengthy form's inputs at the server. But I don't think making db calls on each auto-save action is the best approach to go for.

What would constitute as a good approach to solve this?

Another problem is that I have 3 app servers. So in memory cache wouldn't work.

I was thinking keeping the data in redis and updating it on every call and finally updating the db. But since I have 3 servers how do I make sure the calls are in queue?

Can anyone help with the architecture?

via amit