Slow Security patch deployment due to VMDK write operations

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• Applying security patches on virtual machines is taking longer than expected.
• In vCenter, selecting the VM and navigating to the "Monitor" tab under "Performance" shows high disk latency during normal operations as well.

 

 

Validation:

• In vCenter, selecting the VM under "Monitor" > "Performance" view shows virtual disks are reporting very high write latency while applying security patches on Virtual machines.

 

 

 

Environment

VMware vSphere ESXi 7.0.x

VMware vSphere ESXi 8.0.x

Cause

• The issue is caused by high latency on the underlying storage device, as indicated by the DAVG metric, which measures the average response time per command sent to the device. Prolonged high latency suggests that the storage device or disk is not performing optimally.

 

• ESXTOP stats show the DAVG value is high as shown in the figure below:

        To identify storage performance issues on ESXi on per lun basis refer to this article:   Using esxtop to identify storage performance issues for ESXi 

Resolution

To resolve this issue, engage the storage vendor to analyze storage array performance metrics for latency or bottlenecks and address potential problems with the storage hardware or configuration.