Question: Should I buy or build my own cheap NAS?
The main advantages I see in building your own server / NAS:
Speed – The benchmark results of most the cheaper NAS boxes will show one common trait; they are slow. By building your own server with a fast CPU and a ton of memory, both very cheap these days, you can get much more predictable performance results.
Flexibility – You’ll gain the ability to add features without being limited by the NAS vendor. (iSCSI, ATAoE, etc.). Also, you’ll have an extra PC to run many different programs. (PVR/DVR, VPN/SSH gateway, version control repository, web/mail server, etc.)
Expansion – A standard PC case can provide much greater expansion room for additional drives beyond the drive bays available in proprietary NAS devices.
Reliability – By using software RAID on your server, you are not limited to a particular hardware controller to access/recover your data. If the controller dies a few years down the road, there are no guarantees that the hardware manufacturer is still making that NAS device, or that they haven’t changed the RAID / FW implementation of their new devices that make it impossible to recover your data. Software RAID will let you plug your drives into any Windows/Linux box (depending on which you choose) and easily give access to your data.
Obviously buying your own cheap NAS moves much of the upfront work off to the NAS vendor. You don’t have to source the components, assemble, and troubleshoot the system. Many of the NAS vendors even have a software repository available to install and run different applications with a click of a button. If you just want something turnkey, and the above points are not really a concern, there are some great NAS vendors out there building fairly robust systems, such as Synology and Qnap.