Nutanix Inefficient VM : Bully, Zombie, Constrained, Over-provisioned VM’s Trouble-shooting

To Continuously analysis of Nutanix Inefficient VMs profile i.e Bully, Zombie, Constrained and Over-provisioned Virtual machine (VM) is dedicated monitoring task in every virtualized infrastructure to keep eagle eyes on running virtual machine in critical production.


It is very important to keep monitoring the virtual machines compute ( vCPU, vMemory ) and storage utilization on regular basis to track down the logged or upcoming VM’s inefficiency issue.

Nutanix integrated VM efficiency core monitoring tool to detect Nutanix inefficient VM profile i.e Bully, Zombie, Constrained and Over-provisioned from Prism Central appliance ( Prism central deployed as VM appliance in Nutanix hyper converged infrastructure ) to monitor each VM’s behavior in Nutanix environment.
Learn more to deploy Prism Central

Leaning Index

  • What is Nutnanix VM Efficiency in virtualized infrastructure ?
  • What is Nutanix VM Efficiency tool in Prism Central ?
  • VM Profile : Efficient VM and Inefficient VM ?
  • How to do Inefficient VMs Troubleshooting ?
  • What is VM Right Sizing ?
  • What is Inefficient VM Profiles Best Recommendation ?
  • Prism Central overview video

Lets explore the answer of above questions one by one starts from

VM Efficiency ?

VM Efficiency is the master key of VM performance along with compute resources utilization in expected threshold range.
VMs are determined in good efficiency if they are using expected compute resources to execute the specified application and programs

VM Efficiency Tool In Prism Central

Prism Central has built-in VM behavior learning engine that’s run VM efficiency algorithm periodically to check efficient and inefficient VMs in Nutanix infrastructure.

Prism Central includes machine-learning capabilities that analyze resource usage over time and provide tools to monitor resource consumption, identify abnormal behavior, and guide resource planning. These tools include

  • VM “right sizing” where VMs are analyzed and those that exhibit inefficient profiles are identified.
  • Anomaly detection to record when performance or resource usage is outside an expected range based on learned VM baseline behavior.
  • “Smart” alerts that trigger when specified anomalies are recorded.
  • Reports that summarize cluster efficiency.

Virtual Machine (VM) Profile

VM Profile is divided in to two categories
1. Efficient VM Profile
2. Inefficient VM Profile

Efficient VM Profile

If a VM is performing in an expected threshold range of compute and storage I/O, the efficiency is listed as “Good” and VM comes under efficient VM Profile.

Inefficient VM Profile

If a VM is performing in unexpectedly behavior touching lowest or highest threshold of compute and storage I/O that VM comes under Inefficient VM Profile.

Inefficient VM Profiles are

  • Over-provisioned VM
  • Constrained VM
  • Bully VM
  • Inactive VM / Zombie VM

Over-provisioned VM

Over-provisioned VM is the opposite of a constrained VM, meaning it is a VM that is over-sized and wasting resources which are not needed. A VM is considered over-provisioned when it exhibits one or more of the following baseline values, based on the past 30 days:

  • CPU usage < 20% and CPU ready time < 5%
  • Memory usage < 50% (moderately) or < 20% (severely) and memory swap rate = 0 Kbps

To prevent host resource wastage, resize (decrease) the over-provisioned VMs.

Constrained VM

Constrained VM is one that does not have enough resources for the demand and can lead to performance bottlenecks. A VM is considered constrained when it exhibits one or more of the following baseline values, based on the past 30 days:

  • CPU usage > 90% (moderate), 95% (high)
  • CPU ready time > 5% , 10%
  • Memory usage > 90%, 95%
  • Memory swap rate > 0 Kbps (no moderate value)

One or more constrained VMs might cause a performance bottleneck. To provide adequate host resources, resize (increase) the constrained VMs.

Bully VM

Bully VM is one that consumes too many resources and causes other VMs to starve. A VM is considered a bully when it exhibits one or more of the following conditions for over an hour:

  • CPU ready time > 5%
  • Memory swap rate > 0 Kbps
  • Host I/O Stargate CPU usage > 85%

One or more bully VMs might case cluster performance to degrade. Identifying bully VMs can help in analyzing whether one or more of those VMs are misbehaving or need additional resources.

Inactive VM

Inactive VM in either of the following states:

  • Dead VM : A VM is considered dead when it has been powered off for at least 30 days.
  • Zombie VM : A VM is considered a zombie when it is powered on but does fewer than 30 read or write I/Os (total) and receives or transfers fewer than 1000 bytes per day for the past 30 days.

To prevent host resource wastage, delete dead and zombie VMs.

Inefficient VMs Troubleshooting

Follow the steps to find out the inefficient VM in Nutanix infrastructure using Prism central appliance

Step 1 : Log in to the Prism Central

Nutanix Prism
Nutanix Prism Central

Step 2 : Go to Prism Central Dashboard > Click on +Add Widgets

Prism Central Add Widgets
Prism Central Add Widgets

Step 3 : Follow +Add Widgets Wizard

Prism Central VM Efficiency Widget
Prism Central VM Efficiency Widget

Step 4 : Go Back to Prism Central Dashboard and See VM Efficiency Widget

Prism Central VM Efficiency Widget Added on Dashboard
Prism Central VM Efficiency Widget Added on Dashboard

Note : Under VM Efficiency, there is 4 VMs are over-provisoned and 1 VM is Inactive (Dead or Zombie).
Constrained and Bully VMs profiles is not detected any misbehaving VM

Now we will troubleshoot the Over-provisioned and Inactive VMs in following step

Step 5 : Click on any Inefficiency VM Profile ie. “Over-provisioned

Now page will re-direct to Over-provisioned specific VMs

Step 6 : Select a VM and update the compute resources with right sizing

VM Right Sizing

It is useful to look at the profile of your VMs when analyzing problems in a cluster or assessing future resource needs. This can help you identify VMs that are not optimally configured such as ones that consume too many resources, are constrained, are over provisioned, or are inactive.

Inefficient VM Profiles Best Recommendation

Over-provisioned VM : Reduce the compute (vCPU and vMemory) resources as per current utilization to stop the wastage of compute resources.

Constrained VM : Increase the compute (vCPU and vMemory) resources as per demand to enhance the VM’s performance.

Inactive VM : Shutdown or delete the Inactive VM ( Dead VM or Zombie VM ) to stop unnecessarily consuming the resources.

Bully VM : Set the right sizing quota on VMs and Pin those kind of VMs on specific host/node to prevent to aggressively eating and interrupting other host resources and running VMs.

Prism and Prism Central Overivew

Prism & Prism Central Overview

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