Mistakes were made?

[HiyaDragon]

I am facing a dilemma with my new server build. I have been collecting components to upgrade from my current HP Z420 Xeon E5-2690 V2 system, which has 128 GB of RAM. I have acquired a PSU, a Ryzen 9 3900X CPU, and an X470 Taichi motherboard that supports ECC. However, due to my lack of research and incompetence, I made a mistake in purchasing the wrong type of memory modules.

Initially, I bought LRDIMMs, but the system would not boot. Thinking that the LR (Load Reduced) technology might be the issue, I exchanged them for R-DIMMs. It was only later that I realized that the AM4 socket of my motherboard only supports unbuffered ECC RAM. Unfortunately, UDIMMs are more expensive than my budget for a 128 GB kit.

My main concern is that I am running a TrueNAS Core VM with an HBA passed through to it, and I have allocated 64 GB of RAM to it. The TrueNAS VM has a 50 TB storage capacity, and I would like to migrate it over to the new system. If I were to use non-ECC RAM, which I know is not recommended but less expensive, would it cause significant issues?

Alternatively, I am considering buying a single 32 GB stick of unbuffered ECC RAM and upgrading over time. However, I have three Ubuntu VMs running on my server, one of which is a Docker host with 20 containers, a Hassio VM, and a TrueNAS VM. Would 32 GB of RAM be sufficient to handle my needs? Kinda feel defeated been collecting parts for the past few months looking for deals and can’t believe I glossed over the fact AM4 only supports Udimms.

[Exard3k]

@HiyaDragon

would it cause significant issues

no.

@HiyaDragon

Would 32 GB of RAM be sufficient to handle my needs?

Well just check memory usage on your hypervisor. If you don’t know how much memory your system uses, no one knows. If it doesn’t fit into 32GB in normal operation, cut down memory allocation for the VMs. TrueNAS runs with 8GB, just don’t expect miracles from ARC.

[HiyaDragon]

I currently have 90GB of memory in use of 128, with 32GB allocated to Truenas and the remaining amount dedicated to VMs in Proxmox. Presently, only 47% of my memory is in use, with 37% being utilized by Truenas and ZFS simply using whatever is available if I understand correctly. It appears that I could allocate 8GB to Truenas for the time being. If I break it down correctly am using around 18gigs without truenas. Just conflicted if I need really need the ECC for home use or just go with consumer kit.