VM Memory Utilization (KB) Discrepancy between Aria Operations (formerly vRealize Operations) and Guest OS

Products

• VCF Operations/Automation (formerly VMware Aria Suite)

Issue/Introduction

The VM Memory Utilization (KB) does not match the memory consumption observed within the Guest OS.

Environment

Aria Operations 8.x

Cause

The observed discrepancy is due to how the "Memory|Utilization (KB)" metrics are collected.

Resolution

The "Memory|Utilization (KB)" is an accurate reading of the overall footprint of the VM within the environment and the observed discrepancy is due to the metric leveraging two separate formulas depending on the running state of VMTools on the VM.

Formula if VMTools is running on the VM:

Memory|Utilization (KB) = Guest|Needed Memory (KB) + ( Guest|Page In Rate per second * Guest|Page Size (KB) ) + Memory|Total Capacity (KB) – Guest|Physically

Formula if VMTools is not running on the VM:

Memory|Utilization (KB) = Memory|Consumed (KB) Memory|Usage (%) will prefer Memory|Non Zero Active (KB)

Note: If the intention is to capture the memory utilization as observed within the Guest OS on Windows VMs then we recommend to use the "Guest|Used Memory (KB)". The "Memory|Used Memory (KB)" is a raw metric based on the following Windows OS memory performance counters formula: In use = Total – (Modified + Standby + Free)

Additional Information

• It is recommended to maintain the default collection cycle of 5 minutes for Aria Operations metrics to balance data accuracy with performance considerations
• Decreasing the collection interval may lead to excessive data collection, potentially impacting vRops storage and performance
• The observed difference in memory usage values is a result of the varying data sources and collection mechanisms used
• The discrepancy is within the expected range and does not indicate any underlying issues