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I don't have any experience with ZFS personally, but my understanding based on reading is that ZFS wants to aggressively cache as many files in memory as possible. It also keeps checksums for files in memory. The TrueNAS community recommends 1 GB of ECC memory per 1 TB of data stored.

I didn't know. Thanks for calling that out!

This seems to be a common sentiment. Right now buddy backup isn't even in planning stages probably. It's just a feature that may or may not happen one day (but probably will given the interest?) Maybe it will require two licenses of hexos, or maybe, given the worry around this, they will commit to having just a single license necessary. That would probably be a bit more complicated to create, but we'll see when the feature comes out.

I'm sure you would be able to find someone on here who would be willing to trade storage with you. We're probably a good ways away from buddy backup being a reality.

Actually - here is the documentation on this from TrueNas - https://www.truenas.com/docs/core/13.0/gettingstarted/corehardwareguide/#error-correcting-code-memory

So one thing that TrueNAS is pretty adamant about, that I haven't seen the HexOS maintainers talk about, is ZFS's heavy recommendation for Error Checking (ECC) memory. ECC Memory historically was only on and supported by server CPU's and motherboards. Ryzen CPUs support ECC memory as well, but the motherboard needs to support it as well. Also the general rule for TrueNas, which would hold here as well, is at least 1 GB of RAM per TB of storage.

How much redundancy do you want, meaning, how many drives do you want to be able to fail before you start losing data? If you want to allow one drive to fail without losing data, then you'll need 2, if you want to allow 2 drives to fail without losing, you'll need 3. These are called Raid-Z1 and Raid-Z2 respectively. You can use this calculator: https://wintelguy.com/zfs-calc.pl

I saw in the 1.0 roadmap blog post: So I have a windows box my kids use for emulation. I was planning on migrating away from synology to TrueNAS as a VM on that machine in the next month or so. I'll delay the project until HexOS is more stable now that I know it's coming. Based on the quote above, it sounds like you guys might be aiming to simplify hardware passthrough. If I could do GPU, and USB passthrough (easily), I might consider using HexOS as the host OS, and running windows as a VM. I'd be interested to know if this is what you meant by the above quote.

It's not really up to the HexOS devs, it's more up to the TrueNAS guys. It was considered and then decided against I believe. For what it's worth, I completely agree. I'd like ARM to be the default, but until the Enterprise NAS ARM demand rises, it seems unlikely. Here is a forum post talking about it: https://www.truenas.com/community/threads/truenas-scale-on-arm-2024-thread.117674/

TrueNas doesn't support ARM. Also, Macs don't have ECC memory. This is what stopped me from getting an M4 Mac Mini for TrueNas, which is applicable for the same reasons for HexOS.

HexOS, being based on TrueNAS, means ZFS is being used under the hood, right? In the announcement video, Linus was talking about Raid-Z1 and Raid-Z2, so I assume this is ZFS based. I'm not an expert here, but here is my understanding: ZFS caches file checksums in memory, and it assumes that the memory checksums are the source of truth, which is why the ECC memory is necessary. If the file checksum gets bit flipped in memory, this can lead to file corruptions. Also, it's averaged that bits are flipped in a computer 1-3 times a year on average, so I believe without ECC, there is some risk. I'd love for someone to jump in here and tell me that I'm wrong, because for the past month I've been jumping through hoops to get a machine with ECC so I could setup TrueNAS locally.