$ 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=678MiB/s][r=173k IOPS][eta 00m:00s]
test: (groupid=0, jobs=1): err= 0: pid=3619: Sat Jan  9 16:14:53 2021
  read: IOPS=174k, BW=682MiB/s (715MB/s)(10.0GiB/15023msec)
        [ ... ]
Run status group 0 (all jobs):
   READ: bw=682MiB/s (715MB/s), 682MiB/s-682MiB/s (715MB/s-715MB/s), io=10.0GiB (10.7GB), run=15023-15023msec
Disk stats (read/write):
    md0: ios=2598587/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%, aggrios=1310720/0, aggrmerge=0/0, aggrticks=25127/0, aggrin_queue=64, aggrutil=99.13%
  nvme0n1: ios=2621440/0, merge=0/0, ticks=50255/0, in_queue=128, util=99.13%
  sdc: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%