How to Add Custom Disks with Drive Letters and Labels in Aria Automation (VMware by Broadcom)

If you’re working with Aria Automation (formerly vRealize Automation) and want to give users the ability to add extra disks to a Windows VM — and define their drive letter and volume label — you’re in the right place. This guide shows you how to build a flexible and reusable cloud template (blueprint) that handles additional disks dynamically.

We’ll cover:

• YAML blueprint inputs for user-defined disks
• Cloud-init with PowerShell to configure drives
• Handling drive letter and label assignment dynamically
• Ensuring all disks are initialized and formatted properly

---

Step 1: Define Inputs for Additional Disks

In your Aria Automation blueprint YAML, start by defining an input array that allows users to specify up to 4 additional disks, including their desired SCSI unit number, disk size, drive letter, and volume label.

inputs:
  additionalDisks:
    type: array
    title: Additional Disks
    description: |
      Add extra Windows disks with specified drive letter and label. Max: 4
    minItems: 0
    maxItems: 4
    items:
      type: object
      properties:
        diskController:
          type: string
          title: SCSI Controller
          enum:
            - SCSI_Controller_1
            - SCSI_Controller_2
            - SCSI_Controller_3
            - SCSI_Controller_4
          default: SCSI_Controller_1
        diskUnit:
          type: integer
          title: SCSI Unit Number
          minimum: 1
          maximum: 4
        diskSize:
          type: number
          title: Size (GB)
          minimum: 1
          maximum: 500
        driveLetter:
          type: string
          title: Drive Letter
          pattern: '^[D-Zd-z]{1}

---

Step 2: Define the Resources and Map Disks

In your blueprint’s resources section, define a vSphere machine and dynamically attach the disk definitions:

resources:
  Cloud_vSphere_Machine_1:
    type: Cloud.vSphere.Machine
    properties:
      imageRef: server-2022
      cpuCount: 2
      totalMemoryMB: 4096
      remoteAccess:
        authentication: usernamePassword
        username: Administrator
        password: password!
      cloudConfig: |
        Content-Type: multipart/mixed; boundary="==NewPart=="
        MIME-Version: 1.0

        set_hostname: ${self.resourceName}

        --==NewPart==
        Content-Type: text/x-shellscript; charset="us-ascii"
        MIME-Version: 1.0
        Content-Transfer-Encoding: 7bit
        Content-Disposition: attachment; filename="VM-init.ps1"

        #ps1_sysnative
        $diskConfig = @'
        ${to_json(input.additionalDisks)}
        '@ | ConvertFrom-Json

        $arrNewDisks = Get-Disk | Where-Object { $_.OperationalStatus -eq "Offline" -and $_.PartitionStyle -eq "RAW" }

        $arrNewDisks = $arrNewDisks | Sort-Object Number
        $diskConfig = $diskConfig | Sort-Object diskUnit

        for ($i = 0; $i -lt $arrNewDisks.Count; $i++) {
            $disk = $arrNewDisks[$i]
            if ($i -lt $diskConfig.Count) {
                $driveLetter = $diskConfig[$i].driveLetter
                $label = $diskConfig[$i].diskLabel

                Write-Host "Initializing disk $($disk.Number) as $driveLetter: labeled $label"

                $partition = $disk | Initialize-Disk -PartitionStyle GPT -PassThru |
                             New-Partition -DriveLetter $driveLetter -UseMaximumSize

                Format-Volume -DriveLetter $driveLetter -FileSystem NTFS -NewFileSystemLabel $label -Confirm:$false
            }
        }

        $drives = Get-WmiObject Win32_Volume -Filter "DriveType=5"
        $drives | ForEach-Object { 
            (New-Object -ComObject Shell.Application).Namespace(17).ParseName($_.Name).InvokeVerb("Eject") 
        } -ErrorAction SilentlyContinue

      attachedDisks: ${map_to_object(resource.Disks[*].id, "source")}
      customizeGuestOs: false
      constraints:
        - tag: env:vSphere

  Disks:
    type: Cloud.vSphere.Disk
    allocatePerInstance: true
    properties:
      capacityGb: ${input.additionalDisks[count.index].diskSize}
      SCSIController: ${input.additionalDisks[count.index].diskController}
      unitNumber: ${input.additionalDisks[count.index].diskUnit}
      count: ${length(input.additionalDisks)}

---

Step 3: Deploy Your Blueprint

Once your blueprint is created and saved:

1. Deploy a new VM using this template.
2. When prompted, fill in values for the additional disks — for example:

[
  {
    "diskUnit": 1,
    "diskSize": 50,
    "driveLetter": "E",
    "diskLabel": "Data1"
  },
  {
    "diskUnit": 2,
    "diskSize": 100,
    "driveLetter": "F",
    "diskLabel": "Logs"
  }
]

3. After deployment, log in to the VM and verify that:
   • Drives E: and F: exist
   • They are properly formatted
   • The labels are “Data1” and “Logs” respectively

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Conclusion: Automating Windows Disks with Drive Letter Control

This blueprint setup allows for complete flexibility in how extra disks are handled during provisioning in Aria Automation. Whether you’re creating SQL servers, app VMs, or log collectors — giving users the power to assign drive letters and labels during deployment streamlines the provisioning process.