PS -Disk-Usage History

#get disk usage information and export it to a CSV file for trend reporting

Param(
    [string[]]$Computername = $env:COMPUTERNAME
)

#path to CSV file is hard coded because I always want to use this file
$CSV = "c:\work\diskhistory.csv"

#initialize an empty array
$data = @()

#define a hashtable of parameters to splat to Get-CimInstance
$cimParams = @{
    Classname   = "Win32_LogicalDisk"
    Filter      = "drivetype = 3" 
    ErrorAction = "Stop"
}

Write-Host "Getting disk information from $Computername" -ForegroundColor Cyan
foreach ($computer in $Computername) {
    Write-Host "Getting disk information from $computer." -ForegroundColor Cyan
    #update the hashtable on the fly
    $cimParams.Computername = $Computer
    Try {
        $disks = Get-CimInstance @cimparams

        $data += $disks | 
            Select-Object @{Name = "Computername"; Expression = {$_.SystemName}},
        DeviceID, Size, FreeSpace,
        @{Name = "PctFree"; Expression = { ($_.FreeSpace / $_.size) * 100}},
        @{Name = "Date"; Expression = {Get-Date}}
    } #try
    Catch {
        Write-Warning "Failed to get disk data from $($computer.toUpper()). $($_.Exception.message)"
    } #catch
} #foreach

#only export if there is something in $data
if ($data) {
    $data | Export-Csv -Path $csv -Append -NoTypeInformation
    Write-Host "Disk report complete. See $CSV." -ForegroundColor Green
}
else {
    Write-Host "No disk data found." -ForegroundColor Yellow
}

#sample usage
# .\GetDiskHistory.ps1 -Computername DOM1,FOO,Srv1,srv2