I currently have 2 Debian servers (VPS with 4 GB memory) and am hosting a variety of websites of differing importance: some are production sites, while others are demo/staging/test sites. Approximately 15-20 websites, one of which will have a fair amount of traffic soon.
For the moment, I have my production sites deployed on one server and demo/staging/test sites on another. Both servers run Apache and MySQL.
I have read about and understand most of the benefits of separating the database (MySQL) from the web server (Apache, but probably going to switch to nginx). I have no performance problems at the moment, but need to move things around from one server to another and was wondering if it was a good time to reorganise the data on both servers. For the moment I do not have the money to add extra servers in the mix.
My question: Is it better to put all my websites on one of the two servers and their corresponding databases on the other, given that they are split between production and demo/staging/test applications, or would I be better off keeping the separation between production and non production applications (considering security/performance factors)?
Ideally, I would move all non production applications to a third server but for the moment its a no go.