vCenter Deployment Resize Fails with "Insufficient resources on host" via API

Products

• VCF Operations
• VMware Cloud Foundation

Issue/Introduction

• When attempting to resize a vCenter deployment on demand using the VMware Cloud Foundation (VCF) API, the operation fails during the pre-check or execution phase.
• The resize operation may fail with one or more of the following error messages:

Insufficient resources on host - Not enough CPU

Insufficient resources on host - Not enough RAM

Insufficient resources on host - Not enough Disk Storage

Precheck vcenter.deployment.size.precheck.container.resources failed with error: insufficient resources on host

Environment

• VMware Cloud Foundation 9.1
• VCF Operations 9.1

Cause

This issue occurs when the necessary prerequisites for resizing the vCenter Server appliance are not met. The system performs a validation check (pre-check) before allocating additional resources, and if the current environment or host cannot satisfy the requirements, the process is halted.

Resolution

Before initiating a vCenter resize, ensure the following requirements are met:

Prerequisites

1. Deployment Size: The target deployment size must be larger than the current source deployment size.
2. Ongoing Tasks: Ensure no Upgrades (RDU, B2B) or backup/restore operations are currently in progress.
3. High Availability: vCenter High Availability (HA) must be disabled.
4. Snapshots: There must be no active snapshots on the vCenter Server appliance.
5. Latency Sensitivity: The Latency Sensitivity setting must be set to normal, low, or medium.
6. Hot-add: Hot-add for both CPU and Memory must be enabled on the vCenter appliance configuration.
7. Resource Availability: If Distributed Resource Scheduler (DRS) is enabled, resource availability is checked only on the specific host where the vCenter is currently deployed.