Sampling Windows Server performance counters with Get-Counter and exporting them to CSV

Goal

Collect a defined set of Windows performance counters over time from PowerShell, save them to a file that survives the session, and convert between formats for later analysis.

Prerequisites

PowerShell on Windows Server (the built-in Microsoft.PowerShell.Diagnostics module; Export-Counter exists only in Windows PowerShell 5.1, not in PowerShell 7); local reading of most counters works without elevation, while reading from a remote computer needs membership in Performance Monitor Users or Administrators there; enough free disk space, since the output grows with sample count and counter count.

Steps

1. Sample a first-pass set covering the classic four resources: Get-Counter -Counter '\Processor(_Total)\% Processor Time','\Memory\Available MBytes','\PhysicalDisk(_Total)\Avg. Disk sec/Read','\Network Interface(*)\Bytes Total/sec' -SampleInterval 2 -MaxSamples 30. Get-Counter's documentation describes -SampleInterval as the number of seconds between samples and -MaxSamples as how many to collect before stopping.
2. For an open-ended capture during an incident, use -Continuous instead of -MaxSamples; the same documentation describes it as sampling until explicitly stopped (Ctrl+C, or a background job's Stop-Job).
3. Preserve the raw, typed samples rather than flattening them immediately: Get-Counter ... -Continuous | Export-Counter -Path C:\perf\capture.blg -FileFormat BLG. Export-Counter's documentation lists -FileFormat values including BLG (the native binary performance-log format) and CSV; writing BLG first keeps every field even if the eventual analysis tool prefers something else. Run this in Windows PowerShell 5.1 (powershell.exe); an existing output file needs -Force to be overwritten.
4. Bound the capture with a computed -MaxSamples (interval × samples = window) instead of relying on someone to interrupt it. A background job (Start-Job) ends when the PowerShell session that started it closes; for a capture that must outlive the session, run the script as a scheduled task (or use a logman data collector set).
5. Convert the capture afterwards: relog C:\perf\capture.blg -f CSV -o C:\perf\capture.csv. The relog command-line reference describes it as extracting performance counter data and converting it into the format given with -f, so a .blg captured in the field can still be reshaped into CSV later even without the original Export-Counter command.
6. For a live, no-setup view of the same categories at the console, Resource Monitor (resmon.exe) shows the equivalent CPU, memory, disk and network views without a script.

Expected result

A .blg file (and, after relog, a .csv) containing every sample of the requested counters across the whole capture window, surviving the session when it was run as a scheduled task.

Limits and test basis

Counter set and counter names are localized: on a non-English Windows installation the English paths above fail and the local names are needed (Get-Counter -ListSet * shows the names and paths the machine actually uses). Wildcard instance syntax ((*)) must match instances that exist; a counter set requiring a role or driver that is not installed returns an error rather than a zero.