This was enough to cause it to reboot:
	
		
			
		
		
	
	
		
			
		
		
	
A few seconds after performing this task, that's when it rebooted. Is there something telling it "after writing a file, go ahead and force-reboot the system"?
	
		
	
	
		
		
			An Optane metadata vdev with a SSD pool? That's borderline crazy.
You have not fully described your system and how everything is wired and powered. From the symptoms, it could be that there's enough power for reading but not for writing.
		
		
	 
Hardware Specs
- Chassis: 45Drives Storinator XL60.
 
- Motherboard: Supermicro HT12SSL-NT.
 
- CPU: AMD Epyc 7313p (16-core).
 
- RAM: 256GB -> 8 sticks of 32GB DDR4 3200.
 
- PCIe1: ConnectX-6 -> PCIe 4.0 x4 -> 2-port 25Gb SFP28.
 
- PCIe2: LSI 9305 24i -> PCIe 3.0 x8 (all 6 ports plugged into direct-attach backplanes with 24 SSDs).
 
- PCIe3: LSI 9305 24i -> PCIe 3.0 x8 (all 6 ports plugged into direct-attach backplanes with 24 SSDs).
 
- PCIe4: LSI 9305 24i -> PCIe 3.0 x8 (all 6 ports plugged into direct-attach backplanes with 24 SSDs).
 
- PCIe5: LSI 9305 24i -> PCIe 3.0 x8 (all 6 ports plugged into direct-attach backplanes with 24 SSDs).
 
- PCIe6: LSI 9305 24i -> PCIe 3.0 x8 (all 6 ports plugged into direct-attach backplanes with 24 SSDs).
 
- PCIe7: LSI 9305 16e -> PCIe 3.0 x8 (3 ports plugged into SAS expanders in another Storinator XL60 chassis with 60 HDDs.
 
- NVMe1: 960GB Intel Optane 905p -> PCIe 3.0 x4
 
- NVMe1: 960GB Intel Optane 905p -> PCIe 3.0 x4
 
- SlimSAS1: SlimSAS to 2 x U.2 -> 2 x 960GB Intel Optane 905p -> PCIe 3.0 x4
 
- SlimSAS2: SlimSAS to 2 x miniSAS HD (only 6 SSDs connected, but both cables plugged in)
 
There are no free PCIe ports in this system; although, if I wanted to use bifurcation, there are an additional 20 lanes on the x16 PCIe ports.
zpool Specs
My main Bunnies zpool is gonna change to a multi-vdev dRAID configuration once I figure out what's wrong. When copying snapshots to my HDD pool, some were missed, so I need to copy those again.
- boot-pool -> 2 x 60GB Corsair Force SSDs
 
- TrueNAS-Apps -> 2 x 2TB Crucial MX500 SSDs
 
- Bunnies
-> 80 x 2TB and 4TB Crucial MX500 SSDs and 4 x 960GB Intel Optane 905p
-> This is where I store my files.
-> I backup this pool to Wolves and also to another zpool on an offsite NAS. 
- Wolves
-> 60 x 10TB HGST Helium HDDs and 2 x 2TB Crucial MX500 SSDs as metadata.
-> All data in this pool is a backup of Bunnies and another pool on my offsite NAS. 
Code:
# zpool status -vL
  pool: Bunnies
 state: ONLINE
  scan: scrub repaired 0B in 08:58:36 with 0 errors on Wed Dec  6 14:05:11 2023
remove: Removal of vdev 1 copied 1.79T in 1h37m, completed on Tue Oct 31 07:02:38 2023
        955M memory used for removed device mappings
config:
        NAME           STATE     READ WRITE CKSUM
        Bunnies        ONLINE       0     0     0
          mirror-0     ONLINE       0     0     0
            sdch2      ONLINE       0     0     0
            sdcp2      ONLINE       0     0     0
          mirror-2     ONLINE       0     0     0
            sdfc2      ONLINE       0     0     0
            sdw2       ONLINE       0     0     0
          mirror-3     ONLINE       0     0     0
            sdg2       ONLINE       0     0     0
            sdi2       ONLINE       0     0     0
          mirror-4     ONLINE       0     0     0
            sdfj2      ONLINE       0     0     0
            sde2       ONLINE       0     0     0
          mirror-5     ONLINE       0     0     0
            sdfo2      ONLINE       0     0     0
            sdaa2      ONLINE       0     0     0
          mirror-8     ONLINE       0     0     0
            sdae2      ONLINE       0     0     0
            sdff2      ONLINE       0     0     0
          mirror-11    ONLINE       0     0     0
            sdfi2      ONLINE       0     0     0
            sdz2       ONLINE       0     0     0
          mirror-15    ONLINE       0     0     0
            sdfp2      ONLINE       0     0     0
            sdfe2      ONLINE       0     0     0
          mirror-16    ONLINE       0     0     0
            sdh2       ONLINE       0     0     0
            sdfr2      ONLINE       0     0     0
          mirror-17    ONLINE       0     0     0
            sdv2       ONLINE       0     0     0
            sdfg2      ONLINE       0     0     0
          mirror-18    ONLINE       0     0     0
            sdfh2      ONLINE       0     0     0
            sdfd2      ONLINE       0     0     0
          mirror-20    ONLINE       0     0     0
            sdf2       ONLINE       0     0     0
            sdfq2      ONLINE       0     0     0
          mirror-24    ONLINE       0     0     0
            sdk2       ONLINE       0     0     0
            sdcq2      ONLINE       0     0     0
          mirror-26    ONLINE       0     0     0
            sdad2      ONLINE       0     0     0
            sdd2       ONLINE       0     0     0
          mirror-27    ONLINE       0     0     0
            sdco2      ONLINE       0     0     0
            sdca2      ONLINE       0     0     0
          mirror-28    ONLINE       0     0     0
            sdcn2      ONLINE       0     0     0
            sdal2      ONLINE       0     0     0
          mirror-29    ONLINE       0     0     0
            sdce2      ONLINE       0     0     0
            sdn2       ONLINE       0     0     0
          mirror-31    ONLINE       0     0     0
            sdeh2      ONLINE       0     0     0
            sdan2      ONLINE       0     0     0
          mirror-32    ONLINE       0     0     0
            sdcg2      ONLINE       0     0     0
            sda2       ONLINE       0     0     0
          mirror-33    ONLINE       0     0     0
            sdc2       ONLINE       0     0     0
            sdb2       ONLINE       0     0     0
          mirror-34    ONLINE       0     0     0
            sdcb2      ONLINE       0     0     0
            sdp2       ONLINE       0     0     0
          mirror-35    ONLINE       0     0     0
            sdcf2      ONLINE       0     0     0
            sdq2       ONLINE       0     0     0
          mirror-36    ONLINE       0     0     0
            sdfb2      ONLINE       0     0     0
            sdao2      ONLINE       0     0     0
          mirror-37    ONLINE       0     0     0
            sdai2      ONLINE       0     0     0
            sdcv2      ONLINE       0     0     0
          mirror-38    ONLINE       0     0     0
            sdcl2      ONLINE       0     0     0
            sdaq2      ONLINE       0     0     0
          mirror-39    ONLINE       0     0     0
            sdap2      ONLINE       0     0     0
            sdfk2      ONLINE       0     0     0
          mirror-40    ONLINE       0     0     0
            sdfn2      ONLINE       0     0     0
            sdfl2      ONLINE       0     0     0
          mirror-41    ONLINE       0     0     0
            sdfm2      ONLINE       0     0     0
            sdcj2      ONLINE       0     0     0
          mirror-42    ONLINE       0     0     0
            sdcm2      ONLINE       0     0     0
            sdck2      ONLINE       0     0     0
          mirror-43    ONLINE       0     0     0
            sdj2       ONLINE       0     0     0
            sdah2      ONLINE       0     0     0
          mirror-44    ONLINE       0     0     0
            sdde2      ONLINE       0     0     0
            sdcu2      ONLINE       0     0     0
          mirror-45    ONLINE       0     0     0
            sdcs2      ONLINE       0     0     0
            sdeo2      ONLINE       0     0     0
          mirror-46    ONLINE       0     0     0
            sdaj2      ONLINE       0     0     0
            sdu2       ONLINE       0     0     0
          mirror-47    ONLINE       0     0     0
            sdt2       ONLINE       0     0     0
            sdac2      ONLINE       0     0     0
          mirror-48    ONLINE       0     0     0
            sdaf2      ONLINE       0     0     0
            sdcd2      ONLINE       0     0     0
          mirror-49    ONLINE       0     0     0
            sdci2      ONLINE       0     0     0
            sdak2      ONLINE       0     0     0
          mirror-50    ONLINE       0     0     0
            sdam2      ONLINE       0     0     0
            sdcc2      ONLINE       0     0     0
          mirror-51    ONLINE       0     0     0
            sdo2       ONLINE       0     0     0
            sdep2      ONLINE       0     0     0
          mirror-52    ONLINE       0     0     0
            sdr2       ONLINE       0     0     0
            sdag2      ONLINE       0     0     0
          mirror-53    ONLINE       0     0     0
            sdl2       ONLINE       0     0     0
            sdm2       ONLINE       0     0     0
        special
          mirror-13    ONLINE       0     0     0
            nvme1n1p1  ONLINE       0     0     0
            nvme0n1p1  ONLINE       0     0     0
          mirror-14    ONLINE       0     0     0
            nvme3n1p1  ONLINE       0     0     0
            nvme2n1p1  ONLINE       0     0     0
        spares
          sds2         AVAIL 
errors: No known data errors
  pool: TrueNAS-Apps
 state: ONLINE
  scan: resilvered 232K in 00:00:00 with 0 errors on Wed Dec  6 03:07:23 2023
config:
        NAME          STATE     READ WRITE CKSUM
        TrueNAS-Apps  ONLINE       0     0     0
          mirror-0    ONLINE       0     0     0
            sdfw1     ONLINE       0     0     0
            sdfx2     ONLINE       0     0     0
errors: No known data errors
  pool: Wolves
 state: ONLINE
  scan: scrub repaired 0B in 05:11:50 with 0 errors on Thu Nov 23 10:07:44 2023
config:
        NAME                  STATE     READ WRITE CKSUM
        Wolves                ONLINE       0     0     0
          draid2:5d:15c:1s-0  ONLINE       0     0     0
            sdbt2             ONLINE       0     0     0
            sdbs2             ONLINE       0     0     0
            sdbu2             ONLINE       0     0     0
            sddv2             ONLINE       0     0     0
            sded2             ONLINE       0     0     0
            sdas2             ONLINE       0     0     0
            sddp2             ONLINE       0     0     0
            sdbg2             ONLINE       0     0     0
            sddn2             ONLINE       0     0     0
            sdbl2             ONLINE       0     0     0
            sdbm2             ONLINE       0     0     0
            sdbn2             ONLINE       0     0     0
            sdbi2             ONLINE       0     0     0
            sdbj2             ONLINE       0     0     0
            sdaw2             ONLINE       0     0     0
          draid2:5d:15c:1s-1  ONLINE       0     0     0
            sddx2             ONLINE       0     0     0
            sdax2             ONLINE       0     0     0
            sdda2             ONLINE       0     0     0
            sday2             ONLINE       0     0     0
            sdby2             ONLINE       0     0     0
            sdbv2             ONLINE       0     0     0
            sdbz2             ONLINE       0     0     0
            sdds2             ONLINE       0     0     0
            sdbw2             ONLINE       0     0     0
            sdbx2             ONLINE       0     0     0
            sddt2             ONLINE       0     0     0
            sddq2             ONLINE       0     0     0
            sdar2             ONLINE       0     0     0
            sdbc2             ONLINE       0     0     0
            sddo2             ONLINE       0     0     0
          draid2:5d:15c:1s-2  ONLINE       0     0     0
            sdaz2             ONLINE       0     0     0
            sdcx2             ONLINE       0     0     0
            sdba2             ONLINE       0     0     0
            sdbb2             ONLINE       0     0     0
            sddr2             ONLINE       0     0     0
            sdbd2             ONLINE       0     0     0
            sdbf2             ONLINE       0     0     0
            sdbe2             ONLINE       0     0     0
            sdcr2             ONLINE       0     0     0
            sdbk2             ONLINE       0     0     0
            sdbp2             ONLINE       0     0     0
            sdbh2             ONLINE       0     0     0
            sdea2             ONLINE       0     0     0
            sddz2             ONLINE       0     0     0
            sdee2             ONLINE       0     0     0
          draid2:5d:15c:1s-3  ONLINE       0     0     0
            sdeg2             ONLINE       0     0     0
            sdct2             ONLINE       0     0     0
            sdef2             ONLINE       0     0     0
            sdeq2             ONLINE       0     0     0
            sddu2             ONLINE       0     0     0
            sdei2             ONLINE       0     0     0
            sdat2             ONLINE       0     0     0
            sdec2             ONLINE       0     0     0
            sdau2             ONLINE       0     0     0
            sdeb2             ONLINE       0     0     0
            sdav2             ONLINE       0     0     0
            sddw2             ONLINE       0     0     0
            sdbo2             ONLINE       0     0     0
            sdbq2             ONLINE       0     0     0
            sdbr2             ONLINE       0     0     0
        special
          mirror-4            ONLINE       0     0     0
            sdab              ONLINE       0     0     0
            sdfs              ONLINE       0     0     0
        spares
          draid2-0-0          AVAIL 
          draid2-1-0          AVAIL 
          draid2-2-0          AVAIL 
          draid2-3-0          AVAIL 
errors: No known data errors
  pool: boot-pool
 state: ONLINE
status: Some supported and requested features are not enabled on the pool.
        The pool can still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
        the pool may no longer be accessible by software that does not support
        the features. See zpool-features(7) for details.
  scan: scrub repaired 0B in 00:00:15 with 0 errors on Sat Dec  2 03:45:17 2023
config:
        NAME        STATE     READ WRITE CKSUM
        boot-pool   ONLINE       0     0     0
          mirror-0  ONLINE       0     0     0
            sdft3   ONLINE       0     0     0
            sdfu3   ONLINE       0     0     0
errors: No known data errors 
Summary of the reboot issue
Bunnies is the one that has the force-reboot issue when writing to it. This began happening 3, maybe 4 days ago now?
I thought it was a power issue
2 days before, I had already removed 15 SSDs that I currently wasn't using. After it started happening, I thought it was a power issue, so I removed 48 SSDs (of 85), but still had the problem.
I already planned to add 128 SSD bays in here for my 123 SSDs, so I completely redid the power wiring and removed every one of the 128 SSD slots from the +5V rail on the PSUs. Also note, I swapped the PSUs in this server with the one in the other Storinator XL60 chassis, again, thinking power was the issue.
I thought it was a heat issue
At some point, I noticed heat issues because I shifted all the fans to Noctua NF-12s during this 128 SSD bay transition. I put them all back to stock, and the heat issues went away. Still, I removed the ConnectX-6 card, and the reboots became less frequent.
I only recently found out why:
The 
real problem occurs 
when writing to Bunnies.
Because my PCs backup their data every 12 hours and on idle, when I stepped away from one, it would start writing data to Bunnies; forcing the reboot situation. When I removed the ConnectX-6 and switched to the onboard NICs, the DNS hostname didn't match, so I could only access my NAS by IP. Because of this, my Windows boxes stopped backing up, lengthening the time between reboots to whenever my snapshots ran.
It was the writes
Based on the fact that reboots started occurring about every hour, it was pretty clear those were causing forced reboots since 
I take hourly snapshots.
After disabling all snapshots and backup tasks, and now since Windows can't access the NAS, it was able to successfully stay on for over 10 hours doing a `zpool scrub`. I'm 100% certain now that writes are the issue and only to the Bunnies pool. 
I'm not yet certain if the issue is physical (NVMe or SATA SSDs) or TrueNAS.
How to figure out what's wrong?
Is there a zdb way I can check this out? If it's just a corrupt pool, I already planned to nix it and convert it to dRAID, but I need to first move off some more recent snapshots. That requires manually running `zfs send` to Wolves.