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ONTAP Data Processing latency - Resolution Guide

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Applies to

ONTAP 9

Description 

  • Data Processing (AIQUM) or Data (CLI) actually covers more than just the CPU D-blade delay, it includes the following:
    • CPU D-blade delay
    • WAFL Suspend delay
    • WAFL CP delay 
    • Notes: 
      • WAFL Suspend delay and WAFL CP delay are not as common as the CPU D-blade delay, and they are difficult to troubleshoot. So they are not discussed in this KB
      • In case Data Processing or Data latency is observed and the contents in this KB doesn't help, please contact NetApp Support for further troubleshooting
      • NetApp internal tools (e.g. AIQ PAS) have a more granular latency breakdown to help differentiate these WAFL delays, the mapping for various Delay Centers can be found from What are the Delay Centers from different performance monitoring tools?
  • This CPU D-blade delay is usually shown as follows:
    • Active IQ Unified Manager: latency shown in Data Processing
    • Command line qos statistics volume latency show: latency shown in the Data column

Example:

Cluster::>rows 0;date;qos statistics volume latency show
Workload            ID    Latency    Network    Cluster       Data       Disk        QoS      NVRAM
--------------- ------ ---------- ---------- ---------- ----------  ---------  ---------  ---------
-total-              -   136.49ms    99.00us    70.00us   136.17ms   153.00us        0ms        0ms
vserver1_vol1..   4201   206.05ms   130.00us        0ms   205.88ms    44.00us        0ms        0ms
vserver5_vol8..   7704  1309.00us   351.00us     1.00us   834.00us   114.00us        0ms     9.00us
-total-              -   140.29ms   103.00us    75.00us   139.94ms   174.00us        0ms        0ms
vserver1_vol1..   4201   379.03ms   127.00us        0ms   378.73ms   175.00us        0ms        0ms
vserver5_vol8..   7704     2.02ms   309.00us     1.30us  1820.00us   105.00us        0ms     9.00us

Note: This is a secondary article on how to troubleshoot ONTAP 9 performance, please see the main ONTAP 9 performance troubleshooting Resolution Guide

Procedure

  1. Determine if high CPU is an issue causing latency
  1. Use the qos statistics workload resource cpu show to:
    • Determine top workloads
    • See if internal workloads are running
    • Compare utilization to User-Default or user workloads

Note: wafltop may also be used to check this

Example: CPU is highest on User-Default, so frontend CIFS/FCP/iSCSI/NFS workload is the cause and can be identified by volume in step 3

cluster1::> qos statistics workload resource cpu show
 -node nodeB
Workload               ID   CPU
------------------ ------ -----
-total- (100%)          -   70%
User-Default            -   42%
_SNAPMIRROR             -   20%
_Efficiency_BestEffort  -    8%
  1. Use the qos statistics volume resource cpu show to:
    • Determine top workloads
    • See if user workloads are running (CIFS/FCP/iSCSI/NFS client work)
    • Compare utilization across volumes
cluster1::> qos statistics volume resource cpu show 
-node nodeB
Workload            ID   CPU
--------------- ------ -----
-total- (100%)       -   71%
vs0-wid101         101   22%
file-1-wid121      121   11%
vol0-wid1002      1002    8%
  1. Reduce top workloads
Click for more details
  1. If none of the steps above work:

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