tl;dr my retired parents have rack space available for me to use adjacent to their home theater and I need to replace my old setup with a better, more reliable rack build.

Prior to this, I had an old Raspberry Pi attached to two disks via USB and it worked but wasn't super reliable. I replicate both ZFS and btrfs datasets from my homelab over to their network and the Pi obviously wasn't the best option for this, particularly when buffering large snapshots with limited memory. I definitely need something purpose-built for this to avoid the Pi's pitfalls.

After a recent remodel, my dad put in a half-rack and I've got about a foot of space to work with. The only caveat is that the rack is adjacent to their theater room, so I'd really like to avoid unnecessary noise, otherwise there's a good chance the server will get kicked out of the house.

From the homework I've done so far, it seems like I should get a generic 4U case and build it myself given that most enterprise rack equipment isn't optimized for silent(ish) operation. I'm happy to do this, but it's been years since I've been in a cold aisle racking equipment and so could use some advice if anyone has experience with similar requirements.

Those requirements summarized are:

• Needs to be quiet - I can probably replace many stock fans with Noctua ones.
• Primary purpose for this server will be remote backup storage. I'll be replicating snapshots and so could really use several bays for disks.
• My old Pi-based setup was a pain in the ass to maintain without remote management, so something like IPMI to administer it when it breaks would be a huge plus.

My open questions:

• What's a good generic 4U chassis for this? Ideally something I can modify a bit with things like after-market fans.
• What's a good mainboard/CPU combination that won't require hideous amounts of cooling and thus a big heatsink?
• If anyone has completed similar builds (rack server for remote storage in a living space), any suggestions you might have for the specs (i.e., I don't ever foresee running big hefty VMs on this thing, but quick I/O would be great)