Check Windows disk health and low disk space
List physical disk model, media type, health status and size together with volume capacity and free-space percentage without deleting files or changing storage configuration.
Run the disk health diagnostic
pwsh -NoProfile -File .\Invoke-WindowsDiagnostics.ps1 `
-Disk -PrivacyMode -ExportMarkdownTo change the low-free-space threshold in the standalone module:
pwsh -NoProfile -File .\scripts\disk-health.ps1 `
-LowFreeSpacePercent 20When this guide is useful
- Windows reports that a drive is running out of space.
- Updates, applications or temporary files fail because storage may be insufficient.
- You need a quick list of physical disks and volumes for a support request.
- A storage-related slowdown or error needs basic health context before deeper testing.
What the storage report checks
Physical disks
Disk model, reported media type, operational health and total size from built-in Windows storage sources.
Volumes
Drive letter or mount context, file system, total capacity, free space and free-space percentage.
Low-space findings
A warning is generated when a volume falls below the configured threshold, which is 15% by default.
Unavailable sources
Permission or platform limitations are reported instead of silently presenting missing storage data as healthy.
How to interpret disk health and free space
Low free space can affect unrelated-looking tasks
Windows Update, browser caches, application installers, paging and crash-dump creation all need storage. A nearly full system volume can therefore contribute to failures outside a file-management workflow.
The percentage and absolute space both matter
Fifteen percent of a small drive and fifteen percent of a multi-terabyte drive represent very different absolute capacities. Use the warning as a prompt to review both values and the workload.
A healthy status is not a complete hardware test
The report shows health values exposed by Windows. It does not perform a surface scan, read vendor SMART attributes directly or stress the device. A disk can still require vendor diagnostics when symptoms persist.
Map volumes to the correct physical device
Systems with multiple disks, Storage Spaces, virtual disks or removable media can have a more complex relationship between physical devices and drive letters. Preserve the full report for context.
What the toolkit does not do
- It does not identify which folders consume the most space.
- It does not read every vendor-specific SMART attribute.
- It does not prove that a drive is free from hardware faults.
- It does not modify partitions, volumes or storage pools.
Reasonable next steps
- Record the free-space values before deleting or moving data.
- Confirm which volume contains Windows, applications, pagefiles and user data.
- Use built-in or vendor-supported tools for deeper hardware testing when health warnings or I/O errors persist.
- Back up important data before attempting repair or partition changes.