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Node reporting false IO latency for partner owned disks

Last Updated:

Applies to

  • ONTAP 9
  • FAS Systems
  • AFF Systems


  • High latency is reported against a disk, but the reporting node does not own the disk.  EMS messages will look similar to:
[Node01: disk_latency_monitor:shm.threshold.ioLatency:debug]: Disk 11d.63.9 has exceeded the expected IO latency in the current window with average latency of 580 msecs and average utilization of 29 percent.
  • Node that owns the disk reports no latency issue with the drive.
  • The drive is the single data disk in a 3 disk root aggregate.
Aggregate aggr_root_node02 (online, raid_dp) (block checksums)
  Plex /aggr_root_node02/plex0 (online, normal, active, pool0)
    RAID group /aggr_root_node02/plex0/rg0 (normal, block checksums)

      RAID Disk	Device   	HA  SHELF BAY CHAN Pool Type  RPM  Used (MB/blks)    Phys (MB/blks)
      ---------	------   	------------- ---- ---- ---- ----- --------------    --------------
      dparity 	2a.65.0  	2a    65  0   SA:A   0  FSAS  7200 3807816/7798408704 3815447/7814037168 
      parity  	9a.51.0  	9a    51  0   SA:A   0  FSAS  7200 3807816/7798408704 3815447/7814037168 
      data    	9b.63.9  	9b    63  9   SA:B   0  FSAS  7200 3807816/7798408704 3815447/7814037168

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