Network Management

Understanding the Difference Between Disk Volumes and Component Volumes in SolarWinds Self-Hosted Platform

This article discusses an issue where disk usage in the SolarWinds Platform appears inconsistent due to the presence of two different volume types: Disk Volumes and Component Volumes. It explains how Disk Volumes reflect OS-level storage polled via SNMP, WMI, or Agent, while Component Volumes represent VM-level storage collected from the hypervisor by VMAN

First published date

2/4/2026 10:24 PM

Last published date

2/4/2026 10:40 PM

Overview

In the SolarWinds Platform, storage utilization for servers and virtual machines can appear in two different places: Disk Volumes and Component Volumes.
Although they may represent the “same disk” at first glance, these two volume types come from different data sources and serve different monitoring purposes.

This distinction commonly causes confusion when:

  • Disk usage values differ between widgets

  • Volumes are removed from List Resources but still appear elsewhere

  • Alerts trigger for one volume type but not the other

This article explains what each volume type represents, why differences occur, and how to use them correctly.

 

Disk Volume Widget:

 

Component Volumes:

 

Product section

Network Performance Monitor

Resolution

What are Disk Volumes?

Disk Volumes are node-level volumes (C:, D:, mount points, physical/virtual disks) discovered and polled inside the operating system by NPM/SAM:

  • Polled via SNMP, WMI, or Agent directly on the node.

  • Stored in Orion.Volumes.

  • Shown in widgets such as Disk Volumes and Vital Stats on the Node Details view.

  • Controlled in Settings → Manage Nodes → List Resources (select/unselect volumes per node).

Typical use cases:

  • Monitoring disk usage/thresholds for physical servers and any VM that is also a managed node.

  • Alerting on free space using volume-based alerts that target Orion.Volumes (e.g. “Volume Percent Used > 90%”).

What are Component Volumes?

Component Volumes are virtual machine storage volumes discovered by VMAN from the hypervisor, not from inside the guest OS:

  • Represent volumes attached to a VM at the virtualization layer (e.g., VMDKs, virtual disks).

  • Collected via VMAN poller from vCenter/ESXi or Hyper‑V APIs, i.e., from the hypervisor, not from SNMP/WMI/Agent in the guest.

  • Stored in Orion.VIM.VirtualMachineVolumes and surfaced in widgets like Component Volumes under the Storage or Virtualization views.

  • Continue to appear even if the VM is not a managed node, or if you uncheck volumes in List Resources, because they are tied to the VM object, not the node.

Typical use cases:

  • Monitoring guest storage utilization for VMs when you have VMAN but may not monitor the VM as a node (e.g., CoreOS or restricted OS).

  • Using the “Guest Storage Utilization” or custom VMAN alerts that evaluate VirtualMachineVolumes.SpaceUtilization to detect low free space on VM disks.