You are booting a server machine, you need to import the disk through the
controller as either a non-raid volume or a raid volume. If you are using a
"live" USB, as a Dragonfly USB can be used more-or-less, you still need to
select the device through the boot manager of the machine itself.
md0 and vn0 are raid and machine-raid. You want to find da or ad, I believe.
You should check your system hardware for the RAID controller. You need to
be sure that it will operate as a diskless machine or handle multiple disk
types.
This really has very little to do with Dragonfly. I use a PowerEdge too, it
works great and is a good decision I think.
