FreeBSD ZFS vs. TrueOS ZoF vs. DragonFlyBSD HAMMER2 vs. ZFS On Linux Benchmarks

With TrueOS offering daily snapshots built against the "ZFS on FreeBSD" code derived from OpenZFS / ZFS on Linux, I decided to run some benchmarks to see how the performance compares to that of FreeBSD 12.0 with its ZFS file-system support, DragonFlyBSD 5.2.1 with its HAMMER2 file-system alternative, and then Linux with ZFS/ZoL and other file-system options.