windows_mscluster_virtualdisk_storage_efficiency_percent reports incorrect percentages on Windows Server 2025

[Dominik-esb]

Current Behavior

When using windows exporter on Windows Server 2025, the metric windows_mscluster_virtualdisk_storage_efficiency_percent is showing incorrect percentage values (e.g., 4944.148232179996), while on Windows Server 2022 the value is correct (59.989256094958456). I noticed this discrepancy when comparing the two systems. I will investigate this and plan to open a PR to address the issue.

Expected Behavior

windows_mscluster_virtualdisk_storage_efficiency_percent should report a correct percentage value on Windows Server 2025, similar to the correct value seen on 2022.

Steps To Reproduce

1. Deploy windows exporter on both Windows Server 2022 and Windows Server 2025.
2. Check the metric windows_mscluster_virtualdisk_storage_efficiency_percent.
3. Observe the value difference between 2022 (expected) and 2025 (incorrect).

Environment

• windows_exporter Version: latest (custom build)
• Windows Server Version: 2025
• Working reference: Windows Server 2022

windows_exporter logs

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Anything else?

I will investigate the cause and submit a PR to fix this issue.
On Windows Server 2022: windows_mscluster_virtualdisk_storage_efficiency_percent = 59.989256094958456
On Windows Server 2025: windows_mscluster_virtualdisk_storage_efficiency_percent = 4944.148232179996

[Dominik-esb]

This issue can be assigned to me. As I implemented this metric and I use it in production I'll fix it soon