windows_exporter/docs/runbooks/windowspagefilealmostfull.md

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WindowsPagefileAlmostFull

Meaning

The page file file has been more than the configured share in use for 15 minutes. The default pagefileUsageThreshold is 80 percent of windows_pagefile_limit_bytes, the current size of the file. The alert needs the pagefile collector. A system-managed page file grows up to its maximum when it fills, so a high usage of the current size on such a system shows that the file has already grown.

Impact

When the page file is full, Windows cannot commit more memory. Allocations fail, processes crash with out-of-memory errors, and the system can become unresponsive. The commit limit alert WindowsMemoryCommitHighUsage usually fires at the same time.

Diagnosis

1. Compare windows_pagefile_free_bytes and windows_pagefile_limit_bytes with windows:memory_committed:ratio and windows_memory_available_bytes to see whether physical memory is exhausted too.

2. Find the processes that hold the commit charge:

   Get-Process | Sort-Object PagedMemorySize64 -Descending | Select-Object -First 10 Name, Id, @{n='CommitMB';e={[int]($_.PagedMemorySize64/1MB)}}
   Get-CimInstance Win32_PageFileUsage | Select-Object Name, AllocatedBaseSize, CurrentUsage, PeakUsage
   

3. Check for a recent change: a new workload, a memory leak that grows over days, or a page file that was made smaller or fixed in size.

Mitigation

Stop or restart the process that leaks memory, or move workload off the host. Add physical memory or enlarge the page file through the normal change process; a fixed page file needs enough room for the peak commit charge of the host. Confirm usage falls below the threshold and stays there.