A virtual disk’s provisioned size describes the storage presented to a guest. It does not tell you how much usable space remains on a filesystem inside that guest. Thin provisioning adds another layer: allocated host bytes may differ from both virtual disk size and guest usage.
Label each measurement by source and meaning. Hypervisor storage, datastore capacity, guest partitions and filesystem usage should not be merged into a single percentage. A missing guest observation must not become a reassuring zero.
Review the platform API and supported guest source before promising coverage. Permissions, guest tools, operating system and monitoring profile influence which fields arrive. Check the actual collection result rather than assuming all virtual machines expose the same data.
For capacity review, retain the observation window and unit. Growth of a percentage is a percentage-point change over time. A forecast needs enough comparable history and should show uncertainty when the series is sparse or inconsistent.
Prepared with AI assistance and checked against supported collection and reporting behavior. Verify device scope and permissions for your environment; no customer outcome or vendor endorsement is implied.