Panic: dva_get_dsize_sync(): bad DVA

About a day ago my server started rebooting on its own with the following message:

What exactly is this indicative of?
Is this a fixable issue; if so how?
What is the best way to keep this from happening in the future?

Finity’s End:
Version: FreeNAS 11.2-U6

CPU: Intel - Core i3-6100 3.7GHz Dual-Core Processor
Motherboard: ASRock - E3C236D4U Micro ATX LGA1151 Motherboard
Memory: Kingston - ValueRAM 16GB (1 x 16GB) DDR4-2133 Memory KVR21E15D8/16
Memory: Kingston - ValueRAM 16GB (1 x 16GB) DDR4-2133 Memory KVR21E15D8/16I x3
Boot Pool: Intel - SSD DC S3500 Series 80GB 2.5" Solid State Drive x2
Jail Pool: Crucial - MX300 275GB 2.5" Solid State Drive x2
Jail Pool: Kingston - SUV500 480G 2.5" Solid State Drive x2
HBA: PERC H310 6Gbps PowerEdge R820
Main Storage: Western Digital - Red 3TB 3.5" 5400RPM Internal Hard Drive x8
Power Supply: EVGA - SuperNOVA G3 750W 80+ Gold
Case: Thermaltake - Core V71 Tempered Glass

CPU Cooler: CRYORIG - H7 49.0 CFM CPU Cooler
Case Fan: CRYORIG - XF140 76.0 CFM 140mm Fan
Case Fan: CRYORIG - QF120 Balance 49.0 CFM 120mm Fan x2
Case Fan: Noctua - NF-A9x14 29.7 CFM 92mm Fan
Cabling: Cable Matters Internal Mini-SAS to 4x SATA Forward Breakout Cable 3.3’ x2
Cabling: Monoprice 24-inch SATA III 6.0 Gbps Cable w/Locking Latch - Black x7
Cabling: Cable Matters 3-Pack 15 Pin SATA Power Splitter Cable 8 Inches
Cabling: J&D [3-Pack] 15 Pin SATA Power Extension Cable, Male to Female Cable
Cabling: Cable Matters 24-Pin ATX Power Supply M/F Extension Cable - 12"
Mounts: PCI Slot Bracket Three Fan Rack Mount Set
Mounts: ICY DOCK Rugged Full Metal 6 x 2.5" SATA HDD & SSD HotSwap Backplane Cage Mobile Rack for 5.25" Drive Bay - ToughArmor MB996SP-6SB
Mounts: ICY DOCK DuoSwap Tray-Less 3.5” SATA HDD Mobile Rack and Ultra-Slim 9.5mm ODD Bay for External 5.25” Bay - MB971SPO-B

UPS: CyberPower - CP1350PFCLCD UPS

Completed Build

DVA is a part of ZFS, which leads me to believe something is going on with your ZFS pool. I’d start with a scrub but I’m not fully confident that will fix the issue because I’m not deep enough in the ZFS code to understand exactly what is causing this.

As noted this is a panic; within a few seconds of this message coming up the server reboots and this repeats less than 2 mins after bootup finishes.