Truenas uses KVM for virtual machines. So that will allow GPU passthrough, but may require command line and config files to do it. For docker this seems relevant: https://forums.truenas.com/t/electric-eel-nvidia-gpu-passthrough-support/11797
When you read files from the ZFS filesystem it will automatically keep the files in RAM. This is called the ARC and it is why people frequently recommend having a lot of RAM with ZFS. The ARC is very effective, automatic, and has no risk because it only caches reads. A cache drive is a secondary ARC generally using a fast SSD. The problem is that it generally only helps performance when you are reading lots of small files multiple times. This is because ZFS does so well reading large files from HDD that it doesn’t make much of a difference.
In short: If you already have the drive and want to play with the feature, go for it. But if your going to spend money on the drive, you will probably be better served spending it on more RAM.
I assume the cache drive is for your ZFS pool. You probably don’t need that.
What about GiB?
Intel iGPU are very good for transcoding.
Other people have already talked about why you are having performance issues with the Pi. As for a better NAS solution you will probably be better off with a used desktop PC from the last 10 years. If the computer doesn’t have enough SATA ports you can get a sata addon card or HBA (host buss adapter) addon card flashed in IT mode. You should be able to find a lot of options on eBay. Maybe people can chime in with specific models to look at.
I have had good luck with self hosted Headscale server and Tailscale clients on Pfsense routers creating a mesh network. But I am trusting other people’s networks. So Tailscale clients on each computer and the NAS would be lower risk.
Tailscale. You can make a free account and they have clients for most things. If you want to self host, Headscale.
My setup is very influenced by consolidating multiple hosts to a single host. So far this setup has been extremely stable for me with the only quirk being the Truenas web gui initially loads very slowly if I haven’t accessed in a couple days. I assume it’s because all the memory for that has gone to swap to make space for caching.
Truenas has the primary focus of being a NAS. Running apps or VMs is more of a side thing. It can do these things fine, but because it’s not the primary focus it doesn’t get the same level of polish as the NAS aspects.
My personal solution is to run Proxmox as the host OS with a Truenas VM. Any other services I want to run get to live in VMs or LXC containers. For example all my docker services run across 3 VMs with a docker swarm setup.
Also it’s not as RAM limited because it uses system memory which can be upgraded.
Any reason you need to encrypt the host OS information? I would assume anything interesting would be in the VM and you could probably have the VM encrypt it’s own storage.
To make sure there is not a misunderstanding, the wattage of a PSU is not how much power it will draw. The wattage is how much is can supply. So if you have a 1000w PSU, but all your components draw 200w of power it will use about 200w of power.
Additionally, if you plan to get a lot of HDDs in the future, do some research on power rails. Some PSUs are designed to only be able to supply a small amount of power to things like HDDs because most people only have 1 or 2.
I have used audiobook shelf to read a couple of PDF files. Seemed to work fine. I mostly use it for audio books.
If you have mechanical HDD you may want to get a foam lined case and anti static bags. That should be the best approach to avoid drive damage.
As for leaving things in the rack, I am concerned that road vibration could walk screws out. That would be bad.
As for food functionality it is very comparable to software remote control of a computer. There are 3 key features that stand out:
Edit: Because this is essentially full access to the machine as if you where physically at it, it should be considered a security risk. Not saying that you need to be scared of it, but you should be aware of the risk and protect it from unauthorized access.
If the iGPU is getting the job done, I would leave that alone. You could add a GPU and pass it through to a gaming VM. But that is an entirely different project.
Proxmox is basically a VM management software that runs in a Debian install. You may be able to add it to your current install, but I am not certain about that.
First based on everything I have ever heard, don’t host your own email server. If you want to learn it that’s fine, but don’t do it for something you actually rely on. My understanding it’s a constant miserable slog to keep it functioning.
Second for getting started, get a cheap used computer and install Linux on it. Also be prepared to wipe it and install something different. Docker may be a good place to go next. You can find lots of guides online, there are tones of apps setup to run with docker you can test out. You could also explore virtual machines. Both have the advantage of making it easier to experiment with different things.
Be aware if you have the iGPU as the only video output device and passthrough to a VM it will no longer show what the host system is doing. This would be referred to as a headless server. I would suggest making sure you can SSH into the host before doing that. LearnLinuxTV has guides for how to do that with best security practices.
Docker works differently, so it may not be an issue with that.