Disk Space(Demand) forecast for a virtual machine is reported in downward trend in Aria Operations

Products

• VCF Operations/Automation (formerly VMware Aria Suite)

Issue/Introduction

• Disk Space(Demand) for a VM from the Inventory > Select virtual machine from inventory > Capacity tab, it is observed that the projection for demand is in downwards trend even though this is a actively used virtual machine. In below example, we see the current demand is around 4904 GB whereas the demand in near future reduces 1583 GB:
  
  
  • Current demand:
    
    
    
    
  • Demand projection for future:
    
    
    
    
    
• Virtual machine's  "Guest File System | utilization (GB)" metric reports a large spike on one of the days:
  
  

Environment

Aria Operations 8.18.x

Cause

This issue occurs either when the 'risk level' is set to aggressive for the capacity under the policy or when there are large spikes in the usage for the VM. When there is large spike in disk usage, the forecast engine does not consider this value and it uses a flat line with little bit of lower level for projection.

Resolution

To resolve this issue, ensure the 'risk level' is set to conservative and not aggressive in the policy. If there is any large spikes for "Guest File System | utilization (GB)" metric, reset the forecast calculation start time right after the big jump(For ex: After Oct 6th from the screenshot above).

1. Review the 'risk level' under the policy > capacity > Edit the settings and ensure the value is selected as 'Conservative':
   
   
   
   
2. To reset forecast
   a. Go to the inventory tab > select the virtual machine > capacity tab.
   b. Click on the 'RESET' option under 'TIME REMAINING'.
   c. Once the time is reset, wait for 24 hours and the forecast will be reported in upwards trend.