What is a NAS?
A NAS (Network Attached Storage) is a small computer that sits on your network and contains many large hard drives - like a mini data center for your home. We do this because we want a lot of storage to keep our digital stuff safe. The real trick is balancing how many drives and how much space is necessary.
[Warning: Slightly Nerdy]
For example, if you pick up an off-the shelf Synology or QNAP 4-drive NAS, you will likely end up with a "3+1" configuration. This means you'll be using only three drives for storing data and leaving the fourth exclusively for when a failure occurs. When any one of the drives fail, you can simply replace it and the NAS will heal itself - keeping your data safe.
Keeping your data safe isn't the only benefit to owning a NAS box, but it should certainly be the most important. These devices will appear as one large chunk of storage despite consisting of multiple smaller drives. They can also run services like media sharing through Plex, folder syncing through SyncThing, can organize your photos via Synology Photos, or even be added as a large external drive within Windows and OSX.
To get an visual idea of how quantity vs. sizes of drives work within a NAS, check out Synology's calculator here. Hint: "SHR" and "SHR2" is one and two drive redundancy, respectively.
Should I build or buy a NAS?
Are you a nerd, love to learn cool stuff, like fixing things, and want to constantly bend your stuff to your will? Build it!
Do you like it when things "just work", own an iPhone, and get aggravated when "this damn thing just worked yesterday!"? Buy it.
How Do I Build One?
Building a NAS is the same as building any computer. In fact, you could even use hardware you may already have sitting around the house. If you understand a few basic ideas, you can be up and running in no time.Minimal Components
When building a new computer, my suggestion is always "start with what's most important and work down." For example, a computer I built a few years back was going to fit in a fairly small entertainment center. I started the build with a small form factor case and worked down with what high performance components fit best. Sites like PCPartPicker helped a lot and is a great resource for finding compatibility issues, price calculators, and ideas for full builds. I'll be posting the PCPartPicker NAS build below for you to have a look and play around with.
My 100TB Build
Enter the Shucc!
If you look at current hard drive prices, you'll notice that they're really expensive. For example, 12 and 14 terabyte drives will easily run for $320-400 each. In my opinion, buying these at face value is a terrible idea. A much better option is buying external drives for a fraction of that price.
During recent Christmas sales, I was able to pick up 10 ea. 14 terabyte external hard drives for ~$100 each - saving well over $2,500 for this build.
If you have some guitar picks or old credit cards, use them to pop the tabs holding the drive together and pull out the hard drive waiting inside. There are quite a few potential issues with this technique, but do yourself a favor and research your options versus how much you'll save. You can find a quick and easy guide on "shucc'ing" Western Digital EasyStores here.
Once all the hardware is good to go, we'll need some software to run the computer. For that, we'll need an operating system. The one that I would recommend above all others is FreeNAS. It's a free, open source OS based on FreeBSD Linux. It can easily manage systems as small as a home office or provide a large business with a stable, on-site storage solution. To get set up you'll need to download their ".iso" image here and follow my "How to write .img files" page here. Once you have a flash drive ready, plug it in to your computer and set your computer to boot to it. Typically you'll just need to hit the F12 key when the computer starts and select the flash drive with FreeNAS installed.
The rest is pretty straight forward. FreeNAS also provides a "getting started" page here where you can find great documentation, forums, and instructions to get running. I'd also suggest subscribing to the FreeNAS subreddit for when you want to really nerd out on what your new system is capable of.
Good luck and have fun! If you have any questions, you can always find me on Twitter.