iostat output is incorrect for nvme SSD disks
Issue
- iostat output for nvme disks shows high device utilization and svctm > await time for no or small load conditions
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sdb 0.00 0.35 0.29 0.13 2.29 3.89 14.80 0.01 34.21 1.01 0.04 sda 0.01 5.36 2.25 1.58 18.51 55.56 19.32 0.42 108.88 0.83 0.32 sde 0.00 0.38 0.35 0.12 2.83 3.99 14.29 0.00 4.11 0.07 0.00 nvme0n1 0.00 0.00 2.65 0.92 20.56 11.57 8.99 0.95 15.18 279.26 99.77
- iostat output for nvme disks shows non-zero avgqu-sz and 100% utilization while disk is idle
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util nvme0n1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4285443.30 0.00 0.00 100.00 nvme0n1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4285443.30 0.00 0.00 100.00 nvme0n1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4285443.30 0.00 0.00 100.00 nvme0n1 0.00 0.00 1.00 0.00 4.00 0.00 8.00 4285443.30 0.00 1000.00 100.00 nvme0n1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4285443.30 0.00 0.00 100.00 nvme0n1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4285443.30 0.00 0.00 100.00 nvme0n1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4285443.30 0.00 0.00 100.00
Environment
- RHEL 6.5
- nvme device driver
- NVMe SSD disks
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