Mindaugas from ScienceProg wrote a detailed guide on how to setup a Raspberry Pi to serve as a NAS.
There is a Raspberry Pi 3 out there which is much faster than version 1 and 2. While latest two are faster than first model, Mindaugas thought it would be great to give some purpose to first Raspberry Pi model B. We all share several computers around the house and sometimes need simple file storage solution to make backups, share and store. Rasperry Pi model B is sufficient for simple Network Attached Storage (NAS) solution. It doesn’t need much processing power to manage drive. There is also an option to have torrent client running 24/7. Another benefits of using Raspberry Pi is low power.
Read Mindaugas’ full article via this link