While managing large Broadcom VMware environments, understanding how multiple Virtual Machines virtual disks are mapped across datastores, SCSI controllers, and guest partitions is critical for performance tuning, troubleshooting, and capacity planning. Doing this manually is time-consuming and error-prone—especially when you're dealing with multiple VMs and complex storage configurations.
This article walks you through a PowerShell-based tool that automates the collection of VMware VM disk information using PowerCLI and Windows CIM classes, and renders a dynamic HTML visualization for clear insight. Below is the screenshot of how this visualization looks.
After writing and using by my colleagues I have observed It is been very very useful to detect VM disk mappings.
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#requires -version 5
<#
.SYNOPSIS
Show Vmware Virtual Machine Disks mapping view in GUI HTML.
.DESCRIPTION
Show Vmware Virtual Machine list all Disks mapping view in GUI HTML.
.PARAMETER GroupName
Prompts you provide VM name, vCenter/Esxi credentials and Windows VM credentials to connect VM.
.INPUTS
System.Windows.Forms.Form
.OUTPUTS
HTML Diagram
.NOTES
Version: 1.0
Author: Janvi
Creation Date: 15 May 2024
Purpose/Change: Get Vmware Virtual Machine Disks mapping view in HTML
Useful URLs: http://vcloud-lab.com
Tested on: Windows 2019 DataCenter Edition, PowerShell 7.4.2, vCenter 8.0, Chrome and Edge Browser
.EXAMPLE
PS C:\>. /Show-VMDiskRelationshipMapping.ps1
List all VMware Virtual Machine disk mapping
#>
$details = . $PSScriptRoot\_extras\VMdetailsGUI.ps1 | ConvertFrom-Json
$vmName = $details.vm.vmName
try {
Import-Module VMware.VimAutomation.core -ErrorAction Stop | Out-Null
$vCenterLogin = Connect-VIServer -Server $details.vc.vCenter -User $details.vc.vCenterUser -Password $details.vc.vCenterPassword -ErrorAction Stop
$hdds = Get-VM $vmName -ErrorAction Stop | Get-HardDisk
}
catch {
<#Do this if a terminating exception happens#>
Write-Host $error[0].exception.Message
break
}
$remoteDisksScript = {
if (-not(Test-Path c:\Temp))
{
New-Item -Path C:\ -Name Temp -ItemType Directory -Force
} #if (-not(Test-Path c:\Temp))
$allDrives = Get-CimInstance -ClassName Win32_DiskDrive
$usedDisks = $allDisks= $allDrives | ForEach-Object {
$disk = $_
$partitions = "ASSOCIATORS OF " +
"{Win32_DiskDrive.DeviceID='$($disk.DeviceID)'} " +
"WHERE AssocClass = Win32_DiskDriveToDiskPartition"
Get-CimInstance -Query $partitions | ForEach-Object {
$partition = $_
$drives = "ASSOCIATORS OF " +
"{Win32_DiskPartition.DeviceID='$($partition.DeviceID)'} " +
"WHERE AssocClass = Win32_LogicalDiskToPartition"
Get-CimInstance -Query $drives | ForEach-Object {
[PSCustomObject]@{
DriveLetter = $_.DeviceID.Replace(':','')
Disk = $disk.DeviceID.Substring(4)
PhysicalDiskNo = $disk.DeviceID.Substring(4).TrimStart('PHYSICALDRIVE')
DiskSize = [Math]::Ceiling($disk.Size/1GB)
DiskModel = $disk.Model
Partition = $partition.Name
RawSize = [Math]::Ceiling($partition.Size/1GB)
VolumeName = $_.VolumeName
SizeGB = [Math]::Ceiling($_.Size/1GB)
FreeSpaceGB = [Math]::Ceiling($_.FreeSpace/1GB)
VolumeSerialNo = $_.VolumeSerialNumber
DriveType = $_.DriveType
FileSystem = $_.FileSystem
SerialNumber = $disk.SerialNumber
ScsiBus = $Disk.SCSIBus
SCSILogicalUnit = $disk.SCSILogicalUnit
SCSIPort = $disk.SCSIPort
SCSITargetId = $disk.SCSITargetId
Index = $disk.Index
DiskIndex = $partition.DiskIndex
PartitionIndex = $Partition.Index
} #[PSCustomObject]@{
} #Get-CimInstance -Query $drives | ForEach-Object {
} #Get-CimInstance -Query $partitions | ForEach-Object {
} #$usedDisks = $allDisks= $allDrives | ForEach-Object {
$rawDisks = $allDrives | Where-Object {$_.SerialNumber -notin $usedDisks.SerialNumber}
$i = 100
foreach ($rawDisk in $rawDisks)
{
++$i
$allDisks += [PSCustomObject]@{
DriveLetter = "raw$i"
Disk = $rawDisk.DeviceID.Substring(4)
PhysicalDiskNo = $i
DiskSize = $rawDisk.Size
DiskModel = $rawDisk.Caption
Partition = 'N/a'
RawSize = [Math]::Ceiling($rawDisk.Size/1GB)
VolumeName = 'N/a'
SizeGB = [Math]::Ceiling($rawDisk.Size/1GB)
FreeSpaceGB = 'N/a'
VolumeSerialNo = 'N/a'
DriveType = 'N/a'
FileSystem = 'N/a'
SerialNumber = $rawDisk.SerialNumber
ScsiBus = $rawDisk.SCSIBus
SCSILogicalUnit = $rawDisk.SCSILogicalUnit
SCSIPort = $rawDisk.SCSIPort
SCSITargetId = $rawDisk.SCSITargetId
Index = $rawDisk.Index
DiskIndex = $rawDisk.Index
PartitionIndex = 'N/a'
} #$allDisks += [PSCustomObject]@{
} #foreach ($rawDisk in $rawDisks)
$allDisks #| Export-Csv -NoTypeInformation $PSScriptRoot\DiskInfo.csv
#Import-Csv C:\Temp\DiskInfo.csv
}
# Provid clear text string for username and password
[string]$userName = $details.windows.winUser
[string]$userPassword = $details.windows.winPassword
# Convert to SecureString
[securestring]$secStringPassword = ConvertTo-SecureString $userPassword -AsPlainText -Force
# convert to password object
[pscredential]$credObject = New-Object System.Management.Automation.PSCredential ($userName, $secStringPassword)
try {
$session = New-PSSession -ComputerName $vmName -Credential $credObject #(Get-Credential -UserName 'vcloud-lab\vjanvi' -Message 'Remote Server Credentials')
$allDisks = Invoke-Command -Session $session -ScriptBlock $remoteDisksScript
}
catch {
<#Do this if a terminating exception happens#>
Write-Host $error[0].exception.Message
break
}
#Invoke-VMScript -VM $vmName -ScriptText 'Get-CimInstance -ClassName Win32_BIOS' -ScriptType Powershell -GuestUser 'vcloud-lab.com\vjanvi' -GuestPassword 'Password'
#$allDisks | Import-Csv $PSScriptRoot\DiskInfo.csv
$completeInfo = @()
foreach ($hdd in $hdds)
{
$rawHddUuid = $hdd.extensiondata.backing.uuid
$rawHddUuid = $rawHddUuid.Replace('-','')
$matchedHdd = $allDisks | Where-Object {$_.SerialNumber -eq $rawHddUuid}
$matchedHdd | Add-Member -Name StorageFormat -MemberType NoteProperty -Value $hdd.StorageFormat
$matchedHdd | Add-Member -Name Filename -MemberType NoteProperty -Value $hdd.Filename
$matchedHdd | Add-Member -Name CapacityGB -MemberType NoteProperty -Value $hdd.CapacityGB
$matchedHdd | Add-Member -Name VMName -MemberType NoteProperty -Value $vmName
$matchedHdd | Add-Member -Name HDDName -MemberType NoteProperty -Value $hdd.Name
$matchedHdd | Add-Member -Name ControllerKey -MemberType NoteProperty -Value $hdd.ExtensionData.ControllerKey
$matchedHdd | Add-Member -Name UnitNumber -MemberType NoteProperty -Value $hdd.ExtensionData.UnitNumber
$matchedHdd | Add-Member -Name DataStoreName -MemberType NoteProperty -Value (Get-Datastore -Id $hdd.ExtensionData.Backing.Datastore[0]).Name
$completeInfo += $matchedHdd
}
$completeInfo | Export-Csv -NoTypeInformation -Path $PSScriptRoot\DiskInfo.csv
$drives = Import-Csv $PSScriptRoot\DiskInfo.csv
$physicalDisks = $drives | Group-Object -Property PhysicalDiskNo
$groupNumbering = $physicalDisks.Name | ForEach-Object {[int]$_} | Sort-Object
$links = $null
foreach ($number in $groupNumbering) {
#foreach ($physicaldisk in $physicalDisks) {
$physicaldisk = $physicaldisks | Where-Object {$_.Name -eq $number}
$physicalDriveNo = $physicaldisk.Group[0].Disk
$previousGroupDisk = 1
foreach ($group in $physicaldisk.Group)
{
#https://mermaid.js.org/config/schema-docs/config.html#theme
$links += " {0}({0}: fa:fa-computer) ===> {1};" -f $group.DriveLetter, $physicalDriveNo
if ($group.DriveLetter -notmatch 'raw')
{
$links += " style {0} stroke:#FFFFFF,fill:#ff595e,color:white,fontSize:30px;`n" -f $group.DriveLetter
}
else
{
$links += " style {0} stroke:#FFFFFF,fill:#0a2344,color:white,fontSize:30px;`n" -f $group.DriveLetter
}
if (($physicalDisk.Count -eq 1) -or ($previousGroupDisk -eq 1))
{
$links += " {0} ===> SCSI{1}{2}(SCSI{1}:{2} fa:fa-server);`n" -f $physicalDriveNo, $group.SCSIPort, $group.SCSITargetId
$links += " style {0} stroke:#FFFFFF,fill:#ff924c;`n" -f $physicalDriveNo
$links += " SCSI{0}{1}(SCSI{0}:{1}) -.-> SCSI{2};`n" -f $group.SCSIPort, $group.SCSITargetId, $group.SCSIPort
$links += " style SCSI{0}{1} stroke:#FFFFFF,fill:#ffca3a;`n" -f $group.SCSIPort, $group.SCSITargetId
$links += " SCSI{0} -.-> {1}({2});`n" -f $group.SCSIPort, ($group.HDDName -replace '\s',''), $group.HDDName
$links += " style SCSI{0} stroke:#FFFFFF,fill:#8ac926;`n" -f $group.SCSIPort
$links += " style {0} stroke:#FFFFFF,fill:#1982c4,color:white;" -f ($group.HDDName -replace '\s','')
$links += " {0}({1}) ---> {2}({3} fa:fa-database);" -f ($group.HDDName -replace '\s',''), $group.HDDName, ($group.DataStoreName -replace '\s',''), $group.DataStoreName
$links += " style {0} stroke:#FFFFFF,fill:#6a4c93,color:white;" -f ($group.DataStoreName -replace '\s','')
}
$previousGroupDisk++
}
}
Import-Module "$PSScriptRoot\_extras\EPS\1.0.0\EPS.psm1" -Force | Out-Null
$html = Invoke-EpsTemplate -Path "$PSScriptRoot\_extras\Diagram.eps"
$html | Out-File $PSScriptRoot\DiskMapping.html
"--------------------------------------------------`n"
Write-Host "Open $PSScriptRoot\DiskMapping.html in your favorate browser" -BackgroundColor DarkGreen
"`n--------------------------------------------------"
Disconnect-VIServer * -Force -Confirm:$false
|
Download this script bundle here or it is also available on github.com.
💡 What This Script Does
- Connects securely to vCenter using PowerCLI
- Collects all virtual hard disks (Get-HardDisk) for a specific VM
- Remotely queries the Windows VM for physical disk, partition, and volume info using Get-CimInstance
- Maps each disk’s:
- SCSI Port and Target ID
- Guest Drive Letters
- Volume and FileSystem
- Underlying Datastore in vSphere
- Uses Mermaid.js diagrams to generate an intuitive HTML GUI showing the disk-to-SCSI-to-storage relationships
🎯 Why This Is Useful
- 🔧 Troubleshooting: Quickly identify which virtual disk corresponds to which Windows drive (e.g., if C:\ is actually on a slower datastore).
- 🧱 Infrastructure Audits: See which SCSI controller each disk is attached to.
- 📊 Reporting: Save the HTML output and use it as documentation or attach it to change requests.
- ⚡ Automation-Ready: Easily extend the script to loop through multiple VMs or export JSON/XML reports.
HTML-based diagram that visually connects each guest drive to its virtual disk, SCSI bus, and VMware datastore. Raw disks, formatted drives, and even orphaned volumes are all included for full visibility.
Whether you're a virtualization engineer or a PowerShell enthusiast, this script saves hours of manual mapping and lets you visualize your VM’s disk layout with clarity and precision. It’s an excellent addition to your VMware automation toolkit.
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