Unfortunately I don't have a current hyperfixation at the moment. I'm wrapping up a contract at work and it requires babysitting at all hours of the day. I'm looking to pick up a new video game soon hopefully.
My last hyperfixation was stuffing more hardware into my NAS and it went well. I put a 40gbps Infiniband network card (Mellanox Connect X-3) in it and my desktop, then connected them point to point. The cards were like $20 each which is wild, but they're not exactly plug-and-play. The Infiniband cable that connects them was $30, which was silly compared to the card price.
Infiniband is very interesting and weird. Normally you would use Ethernet to connect, but Infiniband requires its own software stack and compatibility. Infiniband does come with IBoIP, which translates normal applications to Infiniband at the cost of losing the high-performance Infiniband stack. The main thing I use that is Infiniband-compatible is my NFS server for file transfers.
I combine all this with ZFS, 64gb of RAM (I would love 128gb but I would need to buy 4x32gb and I only had 16gb sticks laying around), and a 1TB NVME L2ARC cache to keep all my most-used files in fast flash memory, which lets me get the full 40gbps read speed almost always, even though my spinning rust collection is 54TB (108TB raw).
I also stuck a couple $35 58gb Intel Optane sticks in to use as a mirrored boot drive, and partitioned 25GB off of them for a SLOG device (sort of acts like a write cache), which allows me to write extremely quickly to my ZFS without waiting for it to write to the disks. On very large file transfers this benefit is diminished because it needs to flush the files to disk every 5 seconds, but for 99% of transfers I get the full 40gbps and low latency. Intel Optane sticks or similar are mandatory for a SLOG device because normal SSDs will wear out very quickly in this role.
The speed and latency are nice. All said it probably only cost me like $150 for the upgrades, but I already had a functional NAS beforehand.
OH MY GOODNESS WE HAVE THE SAME INTERESTS. I tried the exact same InfiniBand thing a while back only to realize the cards I bought were either duds or needed some weird server something to make them work -- neither would show up on an lspci, and I wasn't sure how to even begin to diagnose that. I also read online that the throughput of IBoIP was like 7Gbps -- sounds like that's not true?
Also, holy cats! 108 TERABYTES of spinning rust in RAID10? How many hard drives is that? Do you actually have a Storinator in your living room? What do you DO with it?
Also, do you have any cool tips for working with zfs? I've been screwing around a bit with TrueNAS lately and it's been a real pain in the rear. Apparently ZFS remembers the last machine it was mounted from and gets mad if you try to mount it from a different one, plus there's the problem of it being impossible to change the number of drives in an array without creating an entirely new array (have they fixed that yet?). I've been wanting to use btrfs instead but 1) slow and 2) the internet is filled with horror stories about btrfs raid