I need to size a new Windows 2016 server.
My current server is a Windows SBS 2008 machine running Exchange, AD and SQL 2012. There are 15 concurrent users mainly accessing the SQL database through a front-end Accounts application. The current size of all databases is 20Gb and the total disc usage today is approx 400Gb.
In my new world, Exchange will be moved to a hosted solution so all I'm left with is AD, some file and print server and SQL 2012.
My thought is to install a single physical machine split into two virtual servers running Windows 2016 Standard and administered using the free version of 5nine software. One virtual server would be dedicated to SQL2012 and the other to AD and File/Print Server (open to suggestions on this layout).
I would like the server to have a life of about 5 years during which time I would expect the number of concurrent user to increase to about 20.
What architecture would be suitable to meet this requirement? i.e. Disc RAID and size, RAM size etc.