Please evaluate my new TrueNas build

hey everyone… I’m supposed to be getting some money that i’m okay allocating to upgrading my storage setup. I currently have 2 Dell R720XD’s, one running TrueNas Core, the other Scale. They are on small drives, (6TB and 8TB), but I’m getting a new server and new drives.

Here’s the new (to me) hardware:

My plan is to have 4 data VDEV’s of 6 16TB HDDs each, RAIDz2. I’m also going to have 2 hot spare HDDs and a few additional cold storage HDDs.

I’m a little confused on optimizing SLOG for synchronous writes, and L2ARC… my thought is to use mirrored U.2’s for each, and have a couple of cold storage extras. But I also read an article discussing the poor performance of SSDs (including U.2’s on mixed read/writes (something I assume is happening when using drives for SLOG and L2ARC)). The article suggested optane 900 and/or 905’s for mixed read/writes. what do you guys think?

This is just (mostly) for personal use… backing up desktops, backing up various homelab proxmox’s w/ versioning using Proxmox Backup Server pointing at a share, creating SMB share snapshots for versioning, plex, etc. I’m also trying to “future proof” as much as I can in terms of storage volume. Am I overdoing the resiliency? i.e. too many vdevs, or the fact that I’m doing z2 vs z1? or does it seem about right?

I’m also duplicating my very most important 1TB share offsite in s3 compatible storage and might spin up another TrueNas with either 1 or 2 sets of 2 mirrored 16TB drives to backup on site important shares… should give me 16 or 32TB of backup space minus overhead.

Any input is appreciated.

I should point out, so everyone doesn’t have to do the math in their head, I used this site:

and got

only 51% efficiency, but that includes avoiding using the last 20% of the drive space.

The U2 drives for SLOG are probably not needed. I dive into the why in this video:

thanks for the response… I’ll rewatch that vid. I thought SSDs helped w/ log for synchronous writes, but maybe I missed something. I had some family stuff come up yesterday and haven’t had a chance to rewatch the vid yet. but i’m all for saving my pennies if it’s not needed given my situation.

Fast nvme drives for caching might be good, but with the ram that you have, I doubt you will need them. 256gb is a lot.

One note… I’ve been having some issues with my Intel x520-xx cards on my Supermicro X10 based builds. Not really sure what is going on, but I’ve replaced one of them with a cheap solution from 10Gtek, which uses the same chipset. Mostly just a note of warning incase you find slow performance or disconnects.

The single NIC cards I bought are now up to $42 new and coupled with a 10Gtek SFP+ for $18 (multimode fiber). Not sure why I was having disconnects, but it was happening with multiple cards. New card and module fixed it, as well as soon after upgrading all my switches. I have 3 more cards to swap out when time permits, but these other 3 are more stable.