I really like using typeperf for perfmon counter collection. It allows me to save a collection of counters to monitor and store those readings in a csv file for later analysis. Sometimes I end up running the output through the PAL tool. Unfortunately, the PAL tool generates graphs that are fairly narrow. Monitoring sessions of long duration causes these graphs to be really cramped. I wanted a way to split the typeperf output to get a reasonable amount of data points in these graphs. A side benefit is the processing per file is a lot quicker.

The script takes a filepath as its only argument. It splits by the hour and copies the header row to each new file.

param (
[string]$filepath #incoming file
)
#Does the file exist
if (Test-Path $filepath) {
$infile = Get-Item $filepath
$data = Get-Content $infile
}
#if not, exit the script
else {
Write-Warning "Failed to find $filepath"
exit
}
#Get the header to be able to repeat it in each file
$header = $data | Select-Object -First 1
$lastHour = $null
$outFile = $null
#Loop through the data, skipping the header line.
$data | Select-Object -Skip 1 | ForEach-Object {
$date = [DateTime]::Parse([string]$_.Substring(1, [string]$_.IndexOf('"',1)-1))
if($lastHour -eq $null -or $date.Hour -ne $lastHour.Hour -or $outFile -eq $null) {
$lastHour = $date.AddMinutes(-$date.Minute).AddSeconds(-$date.Second)
$outFile = Join-Path $infile.Directory ("{0}_{1}{2}" -f $infile.BaseName, $lastHour.ToString('yyyyMMdd_HHmmss'), $infile.extension)
$header | Out-File $outFile -Encoding UTF8
}
$_ | Out-File $outFile -Encoding UTF8 -Append
}

Update: I cleaned up the script a little based on Jeff’s comments below.