iostat -x and sar -d output shows incorrect high %util values for nvme SSD disks

Solution Verified - Updated -

Issue

  • iostat reports incorrect utilisation for nvme ssd
  • iostat shows bad utilization values for devices with scheduler set to none, for example nvme drives
  • sar -d shows wrong utilisation values for disks
  • sar -d and iostat -x report high disk utilization (%util)

Device:         rrqm/s   wrqm/s     r/s     w/s    rMB/s    wMB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
nvme0n1           0.00     0.00    0.00   51.00     0.00     0.81    32.47     0.99    0.02    0.00    0.02  19.45  99.20
nvme1n1           0.00     0.00    0.00    1.00     0.00     0.01    24.00     0.94    0.00    0.00    0.00 939.00  93.90

Environment

  • Red Hat Enterprise Linux 7.6
  • nvme device driver
  • NVMe SSD disks

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