Performance capacity, or headroom, measures how much work you can place on a node or an aggregate before performance of workloads on the resource begins to be affected by latency. Knowing the available performance capacity on the cluster helps you provision and balance workloads.

What you’ll need

Advanced privilege level commands are required for this task.

About this task

You can use the following values for the -object option to collect and display headroom statistics:

For CPUs, resource_headroom_cpu.
For aggregates, resource_headroom_aggr.

You can also complete this task using ONTAP System Manager and Active IQ Unified Manager.

Steps

Change to advanced privilege level:

set -privilege advanced
Start real-time headroom statistics collection:

statistics start –object resource_headroom_cpu|aggr

For complete command syntax, see the man page.
Display real-time headroom statistics information:

statistics show -object resource_headroom_cpu|aggr

For complete command syntax, see the man page.
Return to administrative privilege:

set -privilege admin

Example

The following example displays the average hourly headroom statistics for cluster nodes.

You can compute the available performance capacity for a node by subtracting the current_utilization counter from the optimal_point_utilization counter. In this example, the utilization capacity for CPU_sti2520-213 is -14% (72%-86%), which suggests that the CPU has been overutilized on average for the past hour.

You could have specified ewma_daily, ewma_weekly, or ewma_monthly to get the same information averaged over longer periods of time.

sti2520-2131454963690::*> statistics show -object resource_headroom_cpu -raw -counter ewma_hourly
  (statistics show)

Object: resource_headroom_cpu
Instance: CPU_sti2520-213
Start-time: 2/9/2016 16:06:27
End-time: 2/9/2016 16:06:27
Scope: sti2520-213

    Counter                                                     Value
    -------------------------------- --------------------------------
    ewma_hourly                                                     -
                         current_ops                             4376
                     current_latency                            37719
                 current_utilization                               86
                   optimal_point_ops                             2573
               optimal_point_latency                             3589
           optimal_point_utilization                               72
     optimal_point_confidence_factor                                1

Object: resource_headroom_cpu
Instance: CPU_sti2520-214
Start-time: 2/9/2016 16:06:27
End-time: 2/9/2016 16:06:27
Scope: sti2520-214

    Counter                                                     Value
    -------------------------------- --------------------------------
    ewma_hourly                                                     -
                         current_ops                                0
                     current_latency                                0
                 current_utilization                                0
                   optimal_point_ops                                0
               optimal_point_latency                                0
           optimal_point_utilization                               71
     optimal_point_confidence_factor                                1
2 entries were displayed.