$ sudo fio --bs=4k --ioengine=libaio --iodepth=32 --size=10g --direct=1 --runtime=60 --filename=/dev/md0 --rw=randwrite --numjobs=1 --name=test test: (g=0): rw=randwrite, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=32 fio-3.12 Starting 1 process Jobs: 1 (f=1): [w(1)][100.0%][w=1441KiB/s][w=360 IOPS][eta 00m:00s] test: (groupid=0, jobs=1): err= 0: pid=3602: Sat Jan 9 16:14:10 2021 write: IOPS=342, BW=1371KiB/s (1404kB/s)(80.5MiB/60145msec); 0 zone resets [ ... ] Run status group 0 (all jobs): WRITE: bw=1371KiB/s (1404kB/s), 1371KiB/s-1371KiB/s (1404kB/s-1404kB/s), io=80.5MiB (84.4MB), run=60145-60145msec Disk stats (read/write): md0: ios=100/20614, merge=0/0, ticks=0/0, in_queue=0, util=0.00%, aggrios=103/20776, aggrmerge=0/0, aggrticks=12/920862, aggrin_queue=899774, aggrutil=97.47% nvme0n1: ios=206/20776, merge=0/0, ticks=24/981, in_queue=40, util=95.01% sdc: ios=0/20776, merge=0/0, ticks=0/1840743, in_queue=1799508, util=97.47%