I want to build a proper server with room for 40+ HDDs to move my media server to and have RAID 1. I know a lot about PCs and software, but when it comes to server hardware I have no clue what I’m doing. How would I go about building a server that has access to 40+ RAID 1’d HDDs?
You need to research raid 1,6,10 and zfs first. Make an informed decision and go from there. You’re basing the number of drives off of (uninformed) assumptions and that’s going to drive all of your decisions the wrong way. Start with figuring out your target storage amount and how many drive failures you can tolerate.
Skip ZFS unless you’re planning to get all 40 drives up front, which is pretty bonkers for a home server setup. Acquiring 40 drives incrementally and you’ll be hit with the hidden cost of ZFS.
That’s definitely something to be aware of, but the vdev expansion feature was mergered and will be released probably this year.
Additionally, it looks like the authors main gripe is the current way to expand is to add more vdevs. If you plan this out ahead of time then adding more vdevs incrementally isn’t an issue, you just need to buy enough drives for a vdev. In homelab use this might an issue, but if OP is planning on a 40 drive setup then needing to buy drives in groups of 2-3 instead of individually shouldn’t be a huge deal.
I think the biggest issue home users will run into (until the finally merged PR gets released later this year) is that as they acquire more drives, compared to a traditional RAID cluster that they could expand, they’re going to see more and more drives proportions being used for parity. Once vdev expansion is possible, the system would be a lot more approachable for home users who doesn’t acquire all the drives up front.
Having said that, this is probably a lot less of a concern for someone intending to setup 40 drives in RAID1, as they’re already ready to use half of it for redundancy…