Skill Level: Moderate
The goal of this guide is to give you a basic overview of Unraid, and to point out things to consider when getting started building/choosing hardware to use as your server.
For a more detailed look at Unraid check out: https://wiki.unraid.net/UnRAID_6/Overview
What is Unraid?
Unraid is an embedded operating system that is designed to provide you with the ultimate control over your hardware. In addition to performing the duties of a robust NAS (network-attached storage), Unraid is also capable of acting as an application server and virtual machine host. Unraid installs to and boots from a USB flash device and loads into a root RAM file system.
At its core, Unraid is a hardware-agnostic solution that can turn almost any 64-bit capable system into a NAS. As the name suggests, Unraid doesn't use RAID as its redundancy method; instead it uses a Parity-Protected Array. In laymans' terms, it writes parity information to a parity drive, meaning if any drive fails the data on that drive can be rebuilt. The array can be expanded and shrunk at any time by adding and removing drives. (If you have ever tried to add or remove a drive from a RAID array you will appreciate how much of a benefit this is.) This is great for scalability; if you are just starting out building a server and don't want to spend all your budget on HDD's, then you could simply buy the minimum plus a bit of overhead. Then, in the future, you can invest some of those hard earned dollars on more drives with minimal effort on your part. What makes Unraid very powerful is the virtualisation capabilities through Docker and KMV. The Unraid team have worked hard to make Docker and KMV seamless parts of Unraid, and for the most part they are very simple to use.
An example of running Docker as part of Unraid is running the following applications in Docker containers to have a powerful home controller, media server, and NAS all in one unit.
Plex
Home Assistant
Node Red
The possibilities are vast of what you can achieve with the combination of Docker and KMV on top of a robust operating system.
Key considerations
Choosing the hardware is key. Unraid is robust and scalable but will always be limited by the hardware.
When planning your system, you need to think about what you want out of your server: what you want it to run, how much you want it to store and how important redundancy and speed are. Then you need to think about the future, and account for scalability. Things you need to understand and research before planning your server's hardware:
How Unraid Parity works (This will help you decide if you have one parity drive or two)
Cache drives in Unraid (This will help you determine how many cache drives you install and the size of these drives)
Docker in Unraid (This is important if you plan to use Unraid to do more than just be a NAS)
Special note: Don't overlook the need for a cache drive. Not having one will mean you are at the mercy of the read/write speed of your drives, and will almost always affect your experience with Docker containers and VM's.