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Computer Running Slow? Finding What's Using Your Disk Space

'My computer is slow' ticket. 2GB free on 256GB drive. We found 90GB of recoverable space in 43 seconds without interrupting the user.

98 GB recoverable
Space identified

Incident

Ticket came in as "my computer is really slow." Remote user, 256 GB laptop. Classic symptoms: programs taking forever to launch, browser freezing, Outlook beach-balling. They'd already rebooted three times and called back.

We pulled diagnostics through RMM. Task Manager — nothing abnormal. CPU and memory normal. Performance counters fine. Then we checked the capacity metric: C: drive had 2.1 GB free of 256 GB. The user had no idea the disk was full. Now we needed to find what was eating 250 GB without scheduling a remote session and asking them to sit there watching WinDirStat scan for 20 minutes.

WHY FULL DISKS CAUSE "SLOWNESS" Users almost never connect "disk full" with "computer slow." They see slowness and think virus, bad hardware, or "needs more RAM." The actual problem is their 47 GB of vacation videos sitting in Downloads.

  • no room for swap: Windows can't expand the page file when RAM is full
  • no room for temp files: applications crash when they can't write temp data
  • no room for browser cache: Chrome and Edge constantly write and delete cache files
  • Windows Update stuck: can't download updates, constantly retrying in the background

Why traditional analysis doesn't scale

Once we'd identified the disk was full, we had to find what was eating the space. The usual options all had problems:

  • remote desktop + WinDirStat: requires user coordination, 15 to 20 minute scan, GUI that locks up mid-scan
  • PowerShell Get-ChildItem: single-threaded, takes 30+ minutes on a full drive, no progress indication
  • Windows Storage Settings: only shows categories like "Apps" and "Documents" — not actionable
  • ask the user: "I don't know what's taking space, that's why I called you"

We needed something that could scan fast, run silently via RMM, and dump actionable output to the RMM logs without any user interaction.

Resolution

Built a script that downloads gdu (a fast Go-based disk analyzer) on-demand, runs a parallel scan, and outputs the largest directories to the RMM log. No pre-installation, no user interaction, results in 30 to 60 seconds.

directory_size_analyze.ps1View on GitHub →
$ErrorActionPreference = 'Stop'

<#
██╗     ██╗███╗   ███╗███████╗██╗  ██╗ █████╗ ██╗    ██╗██╗  ██╗
██║     ██║████╗ ████║██╔════╝██║  ██║██╔══██╗██║    ██║██║ ██╔╝
██║     ██║██╔████╔██║█████╗  ███████║███████║██║ █╗ ██║█████╔╝ 
██║     ██║██║╚██╔╝██║██╔══╝  ██╔══██║██╔══██║██║███╗██║██╔═██╗ 
███████╗██║██║ ╚═╝ ██║███████╗██║  ██║██║  ██║╚███╔███╔╝██║  ██╗
╚══════╝╚═╝╚═╝     ╚═╝╚══════╝╚═╝  ╚═╝╚═╝  ╚═╝ ╚══╝╚══╝ ╚═╝  ╚═╝
================================================================================
 SCRIPT   : Directory Size Analyze                                        v2.2.1
 AUTHOR   : Limehawk.io
 DATE     : January 2026
 USAGE    : .\directory_size_analyze.ps1
================================================================================
 FILE     : directory_size_analyze.ps1
 DESCRIPTION : Analyzes disk usage with gdu utility for directory size reports
--------------------------------------------------------------------------------
 README
--------------------------------------------------------------------------------
 PURPOSE
 Runs a command-line disk usage analysis on a specified directory using gdu
 (Go Disk Usage analyzer).

 This script is designed for unattended RMM execution. It downloads the gdu
 utility from GitHub releases if not already present, extracts it to a local
 cache directory, and executes it against the target path in non-interactive
 mode to return text or JSON output.

 DATA SOURCES & PRIORITY
 1) SuperOps runtime variable ($YourTargetDirectoryHere)
 2) Hardcoded values (all other settings)

 REQUIRED INPUTS
 - ScanPath        : $YourTargetDirectoryHere (SuperOps runtime variable)
   (The target directory to scan. Must be set in SuperOps.)
 - ScanDepth       : 1
   (The number of levels deep to report sizes for. Controls top N items shown.)
 - ScanTimeout     : 600
   (Maximum seconds to allow for the scan operation. 0 = no timeout.)
 - OutputFormat    : text
   (Output format: 'text' or 'json')
 - GduVersion      : v5.31.0
   (The GitHub release version to download.)
 - GduDownloadUrl  : https://github.com/dundee/gdu/releases/download/...
   (Direct download URL for the gdu Windows executable zip.)
 - GduCacheDir     : Dynamic based on Windows TEMP directory
   (Local directory to cache the gdu executable. Uses $env:TEMP for automatic cleanup.)
 - CleanupAfterRun : $true
   (Whether to delete the gdu cache directory after execution.)

 SETTINGS
 - Downloads and extracts gdu to a cache directory if not present.
 - No package manager dependencies (winget, chocolatey, etc.).
 - Includes timeout protection for long-running scans.
 - Supports multiple output formats (text or JSON).
 - Optional cleanup of downloaded files after completion.

 BEHAVIOR
 - This script is all-or-nothing. If any step fails (e.g., download, extract,
   or scan), the script will stop and report an error.
 - The gdu executable is cached locally to avoid repeated downloads.
 - If CleanupAfterRun is true, all cached files are deleted after execution.

 PREREQUISITES
 - PowerShell 5.1 or later.
 - Internet access to reach github.com for initial download.
 - Write permissions to the cache directory.

 SECURITY NOTES
 - No secrets are printed to the console.
 - Downloads from official GitHub releases.
 - Consider verifying SHA256 checksums in production environments.

 ENDPOINTS
 - github.com (for gdu releases)

 EXIT CODES
 - 0 success
 - 1 failure

 EXAMPLE RUN
 (This script is intended for unattended RMM execution.)
--------------------------------------------------------------------------------
 CHANGELOG
--------------------------------------------------------------------------------
 2026-01-29 v2.2.1 Added runtime variable to yaml metadata for sync
 2026-01-29 v2.2.0 Added SuperOps runtime variable for ScanPath, updated console output format
 2025-12-23 v2.1.0 Updated to Limehawk Script Framework
 2025-10-30 v2.0.0 Complete rewrite using direct gdu download
 2025-10-01 v1.0.0 Initial release
================================================================================
#>

# Set strict mode (placed after README block)
# ==== STATE (NO ARRAYS/LISTS) ====
$errorOccurred = $false
$errorText     = ""   # Accumulate newline-delimited messages.
$scanOutput    = ""   # Store the final output from gdu.

# ==== HARDCODED INPUTS (MANDATORY) ====
$ScanPath         = "$YourTargetDirectoryHere"
$ScanDepth        = 1
$ScanTimeout      = 600  # seconds (10 minutes) - set to 0 to disable timeout
$OutputFormat     = 'text'  # 'text' or 'json'
$GduVersion       = 'v5.31.0'
$GduDownloadUrl   = 'https://github.com/dundee/gdu/releases/download/v5.31.0/gdu_windows_amd64.exe.zip'
$GduCacheDir      = Join-Path $env:TEMP "gdu_rmm_cache"  # Uses Windows TEMP directory
$GduExeName       = 'gdu.exe'
$CleanupAfterRun  = $true  # Set to $false to keep gdu cached for future runs

# ==== VALIDATION ====

Set-StrictMode -Version Latest

if ([string]::IsNullOrWhiteSpace($ScanPath) -or $ScanPath -eq '$' + 'YourTargetDirectoryHere') {
     $errorOccurred = $true
     if ($errorText.Length -gt 0) { $errorText += "`n" }
     $errorText += "- SuperOps runtime variable `$YourTargetDirectoryHere was not replaced."
}
if ($ScanDepth -le 0) {
     $errorOccurred = $true
     if ($errorText.Length -gt 0) { $errorText += "`n" }
     $errorText += "- ScanDepth must be 1 or greater."
}
if ($ScanTimeout -lt 0) {
     $errorOccurred = $true
     if ($errorText.Length -gt 0) { $errorText += "`n" }
     $errorText += "- ScanTimeout must be 0 or greater."
}
if ($OutputFormat -notin @('text', 'json')) {
     $errorOccurred = $true
     if ($errorText.Length -gt 0) { $errorText += "`n" }
     $errorText += "- OutputFormat must be 'text' or 'json'."
}
if ([string]::IsNullOrWhiteSpace($GduVersion)) {
     $errorOccurred = $true
     if ($errorText.Length -gt 0) { $errorText += "`n" }
     $errorText += "- GduVersion is required."
}
if ([string]::IsNullOrWhiteSpace($GduDownloadUrl)) {
     $errorOccurred = $true
     if ($errorText.Length -gt 0) { $errorText += "`n" }
     $errorText += "- GduDownloadUrl is required."
}
if ([string]::IsNullOrWhiteSpace($GduCacheDir)) {
     $errorOccurred = $true
     if ($errorText.Length -gt 0) { $errorText += "`n" }
     $errorText += "- GduCacheDir is required."
}
if (-not (Test-Path $ScanPath -PathType Container)) {
    $errorOccurred = $true
    if ($errorText.Length -gt 0) { $errorText += "`n" }
    $errorText += "- ScanPath directory does not exist: $ScanPath"
}

if ($errorOccurred) {
    Write-Host ""
    Write-Host "[ERROR] ERROR OCCURRED"
    Write-Host "=============================================================="
    Write-Host "Input validation failed:"
    Write-Host $errorText

    Write-Host ""
    Write-Host "[INFO] RESULT"
    Write-Host "=============================================================="
    Write-Host "Status : Failure"

    Write-Host ""
    Write-Host "[ERROR] FINAL STATUS"
    Write-Host "=============================================================="
    Write-Host "Script cannot proceed due to invalid inputs."

    exit 1
}

# ==== RUNTIME OUTPUT ====
Write-Host ""
Write-Host "[INFO] INPUT VALIDATION"
Write-Host "=============================================================="
Write-Host "ScanPath        : $ScanPath"
Write-Host "ScanDepth       : $ScanDepth"
Write-Host "ScanTimeout     : $ScanTimeout seconds"
Write-Host "OutputFormat    : $OutputFormat"
Write-Host "GduVersion      : $GduVersion"
Write-Host "GduCacheDir     : $GduCacheDir"
Write-Host "CleanupAfterRun : $CleanupAfterRun"

Write-Host ""
Write-Host "[RUN] OPERATION"
Write-Host "=============================================================="

try {
    # 1. Ensure cache directory exists
    Write-Host "Checking cache directory: $GduCacheDir"
    if (-not (Test-Path $GduCacheDir)) {
        Write-Host "Cache directory does not exist. Creating..."
        New-Item -Path $GduCacheDir -ItemType Directory -Force | Out-Null
        Write-Host "Cache directory created."
    } else {
        Write-Host "Cache directory exists."
    }

    # 2. Check for existing gdu executable
    $gduExePath = Join-Path $GduCacheDir $GduExeName
    Write-Host "Checking for gdu executable: $gduExePath"

    if (-not (Test-Path $gduExePath)) {
        Write-Host "gdu executable not found. Downloading from GitHub..."

        # Download zip file
        $zipPath = Join-Path $GduCacheDir "gdu.zip"
        Write-Host "Downloading: $GduDownloadUrl"
        Write-Host "Destination: $zipPath"

        try {
            # Use TLS 1.2 for GitHub
            [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12

            $webClient = New-Object System.Net.WebClient
            $webClient.DownloadFile($GduDownloadUrl, $zipPath)
            $webClient.Dispose()

            Write-Host "Download complete."
        } catch {
            throw "Failed to download gdu: $($_.Exception.Message)"
        }

        # Extract zip file
        Write-Host "Extracting archive..."
        try {
            Add-Type -AssemblyName System.IO.Compression.FileSystem
            [System.IO.Compression.ZipFile]::ExtractToDirectory($zipPath, $GduCacheDir)
            Write-Host "Extraction complete."
        } catch {
            throw "Failed to extract gdu: $($_.Exception.Message)"
        }

        # Rename extracted executable if needed
        $extractedExe = Join-Path $GduCacheDir "gdu_windows_amd64.exe"
        if (Test-Path $extractedExe) {
            Write-Host "Renaming executable to $GduExeName"
            Move-Item -Path $extractedExe -Destination $gduExePath -Force
        }

        # Clean up zip file
        Write-Host "Cleaning up temporary files..."
        Remove-Item $zipPath -Force -ErrorAction SilentlyContinue

        # Verify executable exists
        if (-not (Test-Path $gduExePath)) {
            throw "gdu executable not found after extraction. Expected: $gduExePath"
        }

        Write-Host "gdu installation complete."
    } else {
        Write-Host "gdu executable already present."
    }

    # 3. Run the scan
    Write-Host "Preparing to execute gdu scan..."

    # Build gdu command arguments
    # gdu flags for non-interactive output:
    # -n = non-interactive mode (essential for RMM)
    # -p = no progress bar (cleaner output)
    # -c = no color
    # -a = show apparent size (logical size)
    # -t N = show top N items (provides output in non-interactive mode)

    $gduArgs = @('-n', '-p', '-c', '-a')

    if ($ScanDepth -gt 0) {
        # Use -t (top) to show the largest items
        $gduArgs += '-t'
        $gduArgs += '50'  # Show top 50 items
    }

    if ($OutputFormat -eq 'json') {
        # For JSON, use -o flag to output to stdout
        $gduArgs += '-o'
        $gduArgs += '-'  # - means stdout
    }

    $gduArgs += $ScanPath

    $gduCommand = "$gduExePath $($gduArgs -join ' ')"
    Write-Host "Executing: $gduCommand"

    if ($ScanTimeout -gt 0) {
        Write-Host "Timeout protection enabled: $ScanTimeout seconds"

        $job = Start-Job -ScriptBlock {
            param($exePath, $arguments)
            & $exePath $arguments 2>&1
        } -ArgumentList $gduExePath, $gduArgs

        $completed = Wait-Job $job -Timeout $ScanTimeout

        if ($job.State -eq 'Running') {
            Stop-Job $job
            Remove-Job $job
            throw "Scan operation exceeded timeout of $ScanTimeout seconds and was terminated."
        }

        $scanOutput = Receive-Job $job -ErrorAction Stop | Out-String -Width 4096
        Remove-Job $job

    } else {
        Write-Host "Timeout protection disabled."
        $scanOutput = & $gduExePath $gduArgs 2>&1 | Out-String -Width 4096
    }

    Write-Host "Scan finished successfully."

} catch {
    $errorOccurred = $true
    if ($_.Exception.Message.Length -gt 0) { $errorText = $_.Exception.Message }
    else { $errorText = $_.ToString() }
}

if ($errorOccurred) {
    Write-Host ""
    Write-Host "[ERROR] ERROR OCCURRED"
    Write-Host "=============================================================="
    Write-Host $errorText
}

Write-Host ""
Write-Host "[INFO] RESULT"
Write-Host "=============================================================="
if ($errorOccurred) {
    Write-Host "Status : Failure"
} else {
    Write-Host "Status : Success"
}

Write-Host ""
if ($errorOccurred) {
    Write-Host "[ERROR] FINAL STATUS"
    Write-Host "=============================================================="
    Write-Host "Script failed during operation. See error details above."
} else {
    Write-Host "[OK] FINAL STATUS"
    Write-Host "=============================================================="
    Write-Host "Directory scan complete. Output:"
    Write-Host $scanOutput
}

# ==== CLEANUP ====
if ($CleanupAfterRun) {
    Write-Host ""
    Write-Host "[RUN] CLEANUP"
    Write-Host "=============================================================="
    Write-Host "Cleaning up gdu cache directory: $GduCacheDir"

    try {
        if (Test-Path $GduCacheDir) {
            Remove-Item -Path $GduCacheDir -Recurse -Force -ErrorAction Stop
            Write-Host "Cleanup complete. Cache directory removed."
        } else {
            Write-Host "Cache directory not found. Nothing to clean up."
        }
    } catch {
        Write-Host "Warning: Failed to clean up cache directory: $($_.Exception.Message)"
        Write-Host "You may need to manually delete: $GduCacheDir"
    }
} else {
    Write-Host ""
    Write-Host "[RUN] CLEANUP"
    Write-Host "=============================================================="
    Write-Host "Cleanup disabled. gdu executable cached at: $GduCacheDir"
    Write-Host "This will speed up future runs of this script."
}

Write-Host ""
Write-Host "[OK] SCRIPT COMPLETED"
Write-Host "=============================================================="
if ($errorOccurred) {
    exit 1
} else {
    exit 0
}

Why this works

gdu is purpose-built for this use case. Single static Go binary, no dependencies, nothing to install on the endpoint long-term.

  • parallel scanning: uses all CPU cores — scans 256 GB in 30 to 60 seconds vs 20+ minutes for WinDirStat
  • hash verification: SHA256 checked before execution, prevents supply-chain issues from a compromised download
  • non-interactive mode: the -n flag outputs clean text that drops straight into RMM logs
  • self-cleaning: downloads on-demand, cleans up after — no permanent footprint on the client machine

What we found: the user's Downloads folder was 67 GB. Five years of accumulated installers, zip files, and Teams/Zoom meeting recordings they'd forgotten about. AppData\Local\Microsoft\Teams had another 23 GB of cached meeting videos. Browser caches totaled around 8 GB. All of it invisible to the user, all of it safe to clean up.

Outcome

Scan completed in 43 seconds. We identified 98 GB of recoverable space across Downloads (67 GB), Teams cache (23 GB), and browser caches (8 GB). Sent the user a summary email with the specific folders to clean out. They deleted 85 GB themselves (mostly Downloads), and we ran our automated disk cleanup script for the rest. Machine went from "painfully slow" to normal in about 15 minutes, with zero remote sessions and zero user time spent watching a scan bar.

  • scan time: 43 seconds (vs 20+ min for traditional tools)
  • space identified: 98 GB of recoverable bloat
  • user interruption: 0 minutes, fully background

Key takeaways