The Raspberry Pi is a popular device for newcomers to run Home Assistant on. It’s small, cheap, quiet, and doesn’t use much electricity. A Raspberry Pi was my gateway drug into home automation and self-hosted software. I’ve since moved on to a “proper” server but the Raspberry Pi is still what I’d recommend if you just want to get your toes wet. Home Assistant currently recommends you run the software on either a Raspberry Pi 3 Model B, a Raspberry Pi 3 Model B+, or Raspberry Pi 4 Model B. In my opinion, you should only be considering one of the three recommended platforms. Let me explain.
Raspberry Pi 3 vs. Raspberry Pi 4 for Home Assistant
As I’ve mentioned, it is not recommended that you attempt to run Home Assistant on anything older than the Raspberry Pi 3 Model B. This includes the original Raspberry Pi and the Raspberry Pi 2. And while the Raspberry Pi Zero might be a popular platform for applications such as Pi-hole, it just isn’t powerful enough to handle Home Assistant.
You might be debating whether to go with a Raspberry Pi 3 Model B/B+ or Raspberry Pi 4 Model B for Home Assistant. While you might be able to find a cheap Raspberry Pi 3, there are some serious drawbacks to that platform, which I’ll discuss next.
The Raspberry Pi 3 networking bottleneck
While the Raspberry Pi 3 Model B and Model B+ do feature a gigabit wired LAN adapter onboard, they are hampered by the USB 2.0 bus speed. I won’t get too technical here but there are some serious drawbacks to this. You should be expecting ~950 Mbps (megabits per second) from a “true” gigabit connection. But because of the Raspberry Pi 3’s networking bottleneck, you will be limited to around ~225 Mbps instead. Such a drop in speed will be noticeable.
Faster USB speeds
The Raspberry Pi 4 Model B also boasts faster USB ports. As usual, there are four in total, but two of them get an upgrade to USB 3.0. This is more important than it might seem. Once you start working with a Raspberry Pi you might make the unfortunate discovery that MicroSD cards aren’t very reliable. They are known to corrupt, especially when data is frequently being written to them. This has led many in the community to move their installation onto an SSD connected via USB.
Better CPU, better GPU, and more RAM
While the Raspberri Pi 3 Model B+ only showed marginal gains in performance when put up against the Raspberry Pi 3 Model B, the Raspberry Pi 4 Model B is a big improvement. The MagPi magazine published some impressive benchmarks after the Raspberry Pi 4 Model B was released.
Both the CPU and GPU have been updated on the Raspberry Pi 4 Model B. The CPU has a slightly higher clock speed and has a newer and more efficient architecture than that found in the Raspberry Pi 3 Model B/B+. While it might not look like much on paper in the real world there is a noticeable difference. The same goes for the GPU, which should be capable of playing 4K/60FPS H.265-encoded video.
The “basic” Raspberry Pi 4 Model B, which is being sold for the same price as the Raspberry Pi 3 Model B and B+ were on introduction, boasts four times the amount of RAM over what is available on the Raspberry Pi 3 Model B/B+. And there are options with 4 GB and even 8 GB. Considering many smartphones ship with over 8 GB of RAM this might not seem like much, but it’s more than enough to run a lightweight Linux distribution and Home Assistant on.
How much RAM does Home Assistant need?
So you’ve decided to go with the Raspberry Pi 4 Model B. Good choice! But you might have noticed that there are different versions available. The Raspberry Pi 4 Model B comes with either 1 GB, 2 GB, 4 GB, or 8 GB of RAM (it appears that the 1 GB model is no longer being produced but you might find still find it for sale).
A Linux engineer would probably tell you that you can never have too much RAM and thus should go with the 8 GB. But let me tell you that Home Assistant doesn’t need a lot of RAM. In fact, you’ll probably get by with just the 2 GB. And at just ~$35 that configuration is a bargain. But if you are planning on using any of the many plugins and want to use the Pi for more than just a gateway drug I’d recommend that you go with at least 4 GB. At ~$55 you still get a lot for your money.
Be warned that the Raspberry Pi 4 Model B with 8 GB requires you to install the 64-bit version of Home Assistant, which isn’t quite as mature as the 32-bit version.
Don’t forget the extras
Be warned, that if you just buy a Raspberry Pi 4 Model B that is all you’re getting. You’ll need a powerful enough power supply (I suggest going with the official one) and potentially a case. I’d also using a wired network connection and not relying on WiFi, so make sure you have a spare ethernet cable lying around. There are also kits available which include everything you need.