I've been asked to spec the server hardware requirements for the application I'm currently developing and I'm not confident in my own abilities to do this correctly. I would ideally like a step by step list of how to do this myself, but reading other similar questions, it is not that straight forward and I will probably get the best answers on here by just specifying what my requirements are.
The app is a WPF thin client which communicates via WCF to the server side application hosted in IIS. Currently there is little business logic requirements but this may well change in later phases of the project and may incorporate WWF for some of these requirements. I'm using NHibernate for the persistence layer and will be using AppFabric for second level caching. Finally the database will be a SQLServer 2008 R2 database.
The sites that I have been asked to spec for are going to have around 20 users. In order to keep costs down, they would like a single box solution which in terms of performance, with this small number of users I believe will be fine however, I appreciate the risks of this both from a security point of view as well as downtime etc. If I am being naive here please let me know.
Unfortunately at this stage I have no idea how much data will need to be stored in the database - ultimately can I just assume that the more data I need to store, the bigger hard-drive I will need?
If I have missed any valuable information then please let me know in the comments.