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PerfLogs C:\PerfLogs

Default output folder of Performance Monitor and logman (.blg, .etl, .csv traces); often empty on a fresh install.

Updated on By AltF4 Formation

What it’s for

C:\PerfLogs is the default location where Performance Monitor (perfmon) and logman write their traces. Microsoft’s documentation cites c:\perflogs\Admin for a collection started with logman. The folder exists from installation, even if no collection ever ran.

What it contains

  • Performance traces (.blg, .etl, .csv) from data collector sets, usually in one subfolder per set, such as Admin.
  • Nothing at all, most of the time.

Risks and best practices

  • Delete traces once analyzed or archived, but keep the folder. Stop any running collection first with logman stop.
  • A long collection fills the system volume quickly. Redirect the output to another disk with logman’s -o option.
  • A trace contains process and machine names, so treat it as internal data.

Useful commands

Fenêtre de terminal
# Data collector sets defined or running
logman query


# Total size of the traces
Get-ChildItem C:\PerfLogs -Recurse -Force -File -ErrorAction SilentlyContinue | Measure-Object -Property Length -Sum

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