View and understand MIG insights

Managed instance group (MIG) insights help you understand the CPU and memory usage of the virtual machine (VM) instances that are part of your MIG. These insights are generated automatically based on system metrics or metrics gathered by the Cloud Monitoring service. You can use these insights to support decisions about resizing your MIG's machine type to more efficiently use VM resources.

For more information about insights, see Insights.

Before you begin

View insights for MIG recommendations

Compute Engine generates machine type recommendations based on resource insights. By viewing insights associated with a specific MIG, you can learn more about the CPU and memory usage for your MIG.

To view the insights that generated a specific recommendation, use the gcloud CLI or the API.

gcloud

To view all the available insights in detail for a specific zone, use the insights list command.

gcloud recommender insights list --project=PROJECT_ID \
  --location=LOCATION \
  --insight-type=INSIGHT_TYPE_ID \
  --format=FORMAT

Replace the following:

  • PROJECT_ID: the ID of your project.
  • LOCATION: the zone that contains the resources for which you want to view insights.
  • INSIGHT_TYPE_ID: the id of the insight type. For a list of the VM insights available, see Types of MIG insights.
  • FORMAT: your preferred output format–for example, json.

A typical output of the insights list command using the json output format might look like the following.

[
  {
    "name": "projects/PROJECT_ID/locations/us-central1-a/insightTypes/google.compute.instanceGroupManager.CpuUsagePredictionInsight/insights/0ec21a13-bb04-3121-7321-dc43a11cc3e3",
    "description": "Predicted CPU usage is 1.5 vCPUs.",
    "targetResources": [
      "//compute.googleapis.com/projects/PROJECT_ID/zones/us-central1-a/instanceGroupManagers/test-instance"
    ],
    "insightSubtype": "CPU_USAGE_PREDICTION",
    "lastRefreshTime": "2021-09-15T06:50:45Z",
    "observationPeriod": "14 days",
    "stateInfo": {
      "state": "ACTIVE"
    },
    "content": {
      "predictedCpuCores": 1.5
    },
    "category": "PERFORMANCE",
    "etag": "fds421j2340",
    "associatedRecommendations": [
      {
         "recommendation": "projects/PROJECT_ID/locations/us-central1-a/recommenders/google.compute.instanceGroupManager.MachineTypeRecommender/recommendations/0fd31b24-cc05-4132-8431-ed54a22dd4f1"
      }
    ]
  }
]

API

To view all the available insights in detail for a specific zone, use the insights.list method.

GET https://recommender.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/insightTypes/INSIGHT_TYPE_ID/insights

Replace the following:

  • PROJECT_ID: the ID of your project.
  • LOCATION: the zone that contains the resources for which you want to view insights.
  • INSIGHT_TYPE_ID: the id of the insight type. For a list of the VM insights available, see Types of MIG insights.

A typical output of the insights.list method might look like the following.

[
  {
    "name": "projects/PROJECT_ID/locations/us-central1-a/insightTypes/google.compute.instanceGroupManager.CpuUsagePredictionInsight/insights/0ec21a13-bb04-3121-7321-dc43a11cc3e3",
    "description": "Predicted CPU usage is 1.5 vCPUs.",
    "targetResources": [
      "//compute.googleapis.com/projects/PROJECT_ID/zones/us-central1-a/instanceGroupManagers/test-instance"
    ],
    "insightSubtype": "CPU_USAGE_PREDICTION",
    "lastRefreshTime": "2021-09-15T06:50:45Z",
    "observationPeriod": "14 days",
    "stateInfo": {
      "state": "ACTIVE"
    },
    "content": {
      "predictedCpuCores": 1.5
    },
    "category": "PERFORMANCE",
    "etag": "fds421j2340",
    "associatedRecommendations": [
      {
         "recommendation": "projects/PROJECT_ID/locations/us-central1-a/recommenders/google.compute.instanceGroupManager.MachineTypeRecommender/recommendations/0fd31b24-cc05-4132-8431-ed54a22dd4f1"
      }
    ]
  }
]

For more information about insights, see the reference docs.

Types of MIG insights

You can use different insights to retrieve information about the performance of your MIGs. Each insight type has specific content attributes.

The following sections provide a reference for the MIG insights available.

CPU usage insight

Compute Engine creates CPU usage insights when the CPU usage of your MIGs has been higher or lower than usual for the last observation period.

The insight type ID is google.compute.instanceGroupManager.CpuUsageInsight.

The available subtypes are:

  • HIGH_CPU_USAGE
  • LOW_CPU_USAGE

These are associated with insight descriptions such as the following:

  • In the last 7 days for 80% of the time, CPU usage was greater than or equal to 83% for the least utilized VM instance. In the last 7 days for 80% of the time, CPU usage was greater than or equal to 93% for the most utilized VM instance.
  • In the last 7 days for 80% of the time, CPU usage was lower than or equal to 10% for the most utilized VM instance. In the last 7 days for 80% of the time, CPU usage was lower than or equal to 3% for the least utilized VM instance.

The following table provides some details about the content associated with CPU usage insights.

Attribute Type Description
pointsForLeastUtilizedVm ARRAY Array of objects. Each object contains the following properties:
  • sampleProbability: (DOUBLE) Relative amount of CPU usage samples below the quantile function value.
  • quantileFunctionValue: (DOUBLE) Upper bound for CPU usage which holds at least part (sample probability) of samples.

    The value represents the ratio of the total amount of vCPUs, and is in the range [0, 1].

pointsForMostUtilizedVm ARRAY Array of objects. Each object contains the following properties:
  • sampleProbability: (DOUBLE) Relative amount of CPU usage samples below quantile function value.
  • quantileFunctionValue: (DOUBLE) Upper bound for CPU usage which holds at least part (sample probability) of samples.

    The value represents the ratio of the total amount of vCPUs, and is in the range [0, 1].

CPU usage prediction insight

Compute Engine creates CPU usage prediction insights to indicate the predicted CPU usage for the following day.

The insight type ID is google.compute.instanceGroupManager.CpuUsagePredictionInsight.

A typical description you can find in this insight is similar to the following:

  • Predicted CPU usage of a single instance is 1.5 vCPUs.

The following table provides some details about the content associated with CPU usage prediction insights.

Attribute Type Description
predicted_cpu_cores DOUBLE Predicted amount of CPU cores.

CPU usage trend insight

Compute Engine creates CPU usage trend insights when CPU usage shows an increasing or decreasing trend in the last observation period.

The insight type ID is google.compute.instanceGroupManager.CpuUsageTrendInsight.

The available subtypes are:

  • CPU_USAGE_INCREASE
  • CPU_USAGE_DECREASE

These are generally associated with insight descriptions such as the following:

  • In the last 7 days, average daily CPU usage has increased by 8% from 65% to 73%.
  • In the last 7 days, average daily CPU usage has decreased by 10% from 55% to 45%.

The following table provides some details about the content associated with CPU usage trend insights.

Attribute Type Description
cpu_usage_percentage_at_start DOUBLE Measured daily mean of CPU usage at the start of the observation period.

The value represents the percentage of the total number of vCPUs, and is in the range [0, 100].

cpu_usage_percentage_at_end DOUBLE Measured daily mean of CPU usage at the end of the observation period.

The value represents the percentage of the total number of vCPUs, and is in the range [0, 100].

cpu_usage_percentage_change DOUBLE Predicted change of daily mean of CPU usage during the observation period.

Prediction uses linear regression to model the change of daily CPU usage.

The value represents the percentage of the total number of vCPUs, and is in the range [0, 100].

Memory usage insight

Compute Engine creates memory usage insights if the memory usage is exceptionally high or low during the observation period.

The insight type ID is google.compute.instanceGroupManager.MemoryUsageInsight.

The available subtypes are:

  • HIGH_MEMORY_USAGE
  • LOW_MEMORY_USAGE

These are generally associated with insight descriptions such as the following:

  • In the last 12 days for 80% of the time, memory usage was greater than or equal to 64%.
  • In the last 7 days for 50% of the time, memory usage was lower than or equal to 10%.

The following table provides some details about the content associated with memory usage insights.

Attribute Type Description
sample_probability DOUBLE Relative amount of memory usage samples below quantile function value.

The value is in the range [0, 1].

quantile_function_lowest_value DOUBLE Upper bound for memory usage which holds at least part (sample probability) of samples for the least utilized VM.

The value represents the ratio of the total amount of memory, and is in the range [0, 1].

quantile_function_highest_value DOUBLE Upper bound for memory usage which holds at least part (sample probability) of samples for the most utilized VM.

The value represents the ratio of the total amount of memory, and is in the range [0, 1].

Memory usage prediction insight

Compute Engine creates memory usage prediction insights to indicate the memory usage predicted for the following day.

The insight type ID is google.compute.instanceGroupManager.MemoryUsagePredictionInsight.

A typical insight description is the following:

  • Predicted memory usage is 1536 MB.

The following table provides some details about the content associated with memory usage prediction insights.

Attribute Type Description
predicted_memory_mb DOUBLE Predicted amount of memory expressed in MB.

What's next