$ sudo fio --bs=4k --ioengine=libaio --iodepth=32 --size=10g --direct=1 --runtime=60 --filename=/dev/md0 --rw=randread --numjobs=1 --name=test
test: (g=0): rw=randread, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=32
fio-3.12
Starting 1 process
Jobs: 1 (f=1)
test: (groupid=0, jobs=1): err= 0: pid=5872: Sat Jan  9 16:35:08 2021
  read: IOPS=251k, BW=979MiB/s (1026MB/s)(2045MiB/2089msec)
       [ ... ]
Run status group 0 (all jobs):
   READ: bw=979MiB/s (1026MB/s), 979MiB/s-979MiB/s (1026MB/s-1026MB/s), io=2045MiB (2144MB), run=2089-2089msec
Disk stats (read/write):
    md0: ios=475015/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%, aggrios=0/0, aggrmerge=0/0, aggrticks=0/0, aggrin_queue=0, aggrutil=0.00%
  sdc: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%
  rd0: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%