$ 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): [r(1)][100.0%][r=3184KiB/s][r=796 IOPS][eta 00m:00s]
test: (groupid=0, jobs=1): err= 0: pid=3467: Sat Jan  9 15:44:42 2021
  read: IOPS=806, BW=3226KiB/s (3303kB/s)(189MiB/60061msec)
     [ ... ]
Run status group 0 (all jobs):
   READ: bw=3226KiB/s (3303kB/s), 3226KiB/s-3226KiB/s (3303kB/s-3303kB/s), io=189MiB (198MB), run=60061-60061msec
Disk stats (read/write):
    md0: ios=48344/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%, aggrios=24217/0, aggrmerge=0/0, aggrticks=959472/0, aggrin_queue=910458, aggrutil=96.15%
  sdd: ios=24117/0, merge=0/0, ticks=976308/0, in_queue=927464, util=96.09%
  sdc: ios=24318/0, merge=0/0, ticks=942637/0, in_queue=893452, util=96.15%