Disk queue length very high in SQL Server 2016
Disc queue is an indication that you have saturated the bandwidth to that disc. It indicates that you might have

slow disk
slow connection to a disk (or vhd)
contention

(or any combination of these)
Look at where those discs are, how they are connected, and what is on them. Troubleshooting techniques depend on whether this is a VM (with VHD) or physical hardware.
I usually have the most success by asking my SAN admin (or VM admin) to issue me a drive (letter) &quot;pinned to a spindle&quot; (and not shared), and &quot;scaling-out&quot; (move my busy(est) DB to the new storage), but again, it depends on your equipment/situation.