As a former FreeNAS (or as it is now called: TrueNAS CORE) user, I was expecting Unraid to require a sizable amount of RAM for an all-round smooth operation. As it turns out, that is not the case as OpenZFS, which is the filesystem TrueNAS CORE uses, and Unraid with the XFS filesystem operate in fundamentally different ways. When used only as network-attached storage (NAS), Unraid’s RAM requirements sit at a modest 2 GB.
When not using Unraid as an application server or virtualization host, the RAM is solely used to load the Unraid operating system from the USB drive at boot. However, if you are building a system with recent components, you might not even be able to find any compatible 2 GB sticks of RAM. That, combined with the fact that you can use your Unraid machine for so much more than just a NAS, is why I recommend you go with at least one stick of 8 GB RAM to start off with.
How much RAM your Unraid machine effectively requires depends very much on your use-case. This article will guide you through the different options and tell you what to look out for. There is no one answer to the question: How much RAM does Unraid need?
How much RAM for an Unraid NAS?
As already mentioned, Unraid, when used only as a NAS and nothing more, isn’t very demanding. You will get away with only adding 2 GB of RAM to your system. However, at some point in the future, you might be interested in setting up some Docker containers or spinning up the odd virtual machine (VM) now and again. That is why one stick of 8 GB or 16 GB RAM is the wiser decision than anything smaller to start off with. This also allows you to better expand your RAM capacity further down the line.
How much RAM for an Unraid application server?
Just as they do on your Windows, macOS, or Linux desktop operating system, applications running in Docker containers on Unraid need a certain amount of RAM. Anything from 8 GB to 16 GB will almost certainly cover your needs if you don’t go overboard and only install what you actually need and uninstall or stop applications you are not using any more.
Keep an eye on your Unraid system’s resources to find out whether your system needs an upgrade or not. Monitoring can easily be done using the web interface or the Glances application, which you can install from the Community Applications. For a better overview and nicer graphs, you can integrate Glances with other applications that might provide an easier to understand web interface, such as Home Assistant.
Reports on RAM usage of Docker containers running on Unraid seem to imply that the requirements aren’t very high. Reddit user /u/Jetboy01 reports that Sonarr, Radarr, Lidarr, Tautilli, Plex, Dolphin, SABnzbd, Deluge, and Pi-hole will run perfectly with just 8 GB of available RAM. Another user in the same thread reports that their 21 Docker containers use just 5.16 GB of RAM.
How much RAM for an Unraid virtualisation host?
Virtual machines (VMs) will be the most demanding use-case when it comes to RAM. You will need to plan what VMs you want to run simultaneously before buying components and purchase RAM accordingly. For example, I wouldn’t dare running Windows with anything less than 8 GB of RAM and would preferably use at least 16 GB. Other operating systems, such as Ubuntu Desktop Edition, will run fine with just 4 GB of RAM.
Depending on how many VMs you intend to use and what operating system you will be using, RAM requirements will greatly vary. For multiple Windows VMs, you might have to max out your motherboard’s capacity, whereas Linux VMs without a desktop environment will require significantly less. To get the most out of what you have, I recommend checking whether what you are trying to achieve could be done in a Docker container.
Does Plex Media Server on Unraid need much RAM?
Plex is one of the most popular applications to run on Unraid. I have found many newcomers asking more experienced Unraid users, how much RAM Plex, running in a Docker container, needs. The good news is that Plex doesn’t use much RAM.
However, there are ways of telling Plex to use available RAM as a transcoding buffer. By doing so, switching from play to pause will be done instantly and scrubbing will be way smoother. Transcoding to RAM has the added benefit that you won’t wear out your SSD as quickly, as RAM isn’t susceptible to the same damage as they are. According to reports on the Unraid forums, “a single stream of video content transcoded to 12mbps [takes] up 430 MB on the root [RAM] filesystem”. Thus, having around 8 GB of available RAM for Plex transcoding should comfortably cover all of your transcoding needs.