https://github.com/freebsd/freebsd/blob/master/sys/dev/mrsas/mrsas_cam.c#L359 ccb->cpi.base_transfer_speed = 150000; What is that used for? I poked around /usr/src/sys and found multiple WTF comments. The reason I ask is i have Samsung EVO 860s plugged into a Dell R720 (via LSI 9361 which is where mrsas comes from (also have mfi disabled)) and seeing da0 speed of 150.000MB/sec in dmesg output is a bit strange. I hacked the source and moved it to 600 and sure enough it now reports 600MB/sec on boot up. I haven't benchmarked old vs new yet because the system in question can't be rebooted for a while.