$ 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=5956: Sat Jan  9 16:38:53 2021
  read: IOPS=256k, BW=998MiB/s (1047MB/s)(2045MiB/2049msec)
        [ ... ]
Run status group 0 (all jobs):
   READ: bw=998MiB/s (1047MB/s), 998MiB/s-998MiB/s (1047MB/s-1047MB/s), io=2045MiB (2144MB), run=2049-2049msec
Disk stats (read/write):
    md0: ios=484146/0, 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%
  sdd: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=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%