Azure Virtual Desktop – Handling Temp Disk and Pagefile Correctly on Azure v6 VM SKUs

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Table of Contents

Why the pagefile matters

In Azure Virtual Desktop (AVD), the Windows pagefile is far more than a legacy configuration item.
In multi-session environments, memory pressure is a daily reality:

Dozens of concurrent user sessions
Multiple Office applications per user
Teams, Outlook, browsers, plugins, etc.

Even when sizing virtual machines generously, RAM exhaustion will happen. When that moment arrives, Windows relies on the pagefile to:

Avoid session crashes
Prevent black screens
Stabilize memory commit limits
Allow applications to allocate virtual memory

If the pagefile is missing, misconfigured, or located on the wrong disk, the results are often:

Failed logons without clear errors
Session host instability under load
“Out of memory” conditions even with free RAM

What changed with Azure v6 VM SKUs

On v5 and earlier Azure VM SKUs, the temporary disk was:

Automatically initialized
Formatted
Made available as a drive (usually D:), ready for use at first boot

This meant you could reliably assume the temp disk existed and had a usable filesystem without doing any setup – perfect for placing the Windows pagefile on it.

With the newer v6 VM SKUs, this assumption no longer holds.

According to Microsoft’s Temp NVMe Disks FAQ:

“Unlike the previous D/E series VMs, the new v6 VMs come with raw, unformatted NVMe disks. Customers should initialize and format the disks into a file system of their preference after the VM starts up.“

In other words:

Azure now presents the temp NVMe disk as raw storage: no filesystem, no drive letter
The guest OS must initialize, format, and mount it before anything (including the pagefile) can be placed on it
After stop/deallocate or maintenance events, the VM boots with the NVMe disks unformatted again, so automation must run on every start to reinitialize them before use

This change was introduced to support higher-performance NVMe storage on v6 VMs (optimized for throughput and IOPS), but it breaks the old assumption that the temp disk is usable immediately upon startup.

Design goals for a reliable AVD pagefile solution

When implementing pagefile automation for Azure Virtual Desktop, especially on v6 NVMe-based VM SKUs the solution must be designed for far more than just disk detection. A reliable approach must account for AVD agent startup behavior, Windows boot timing, and mandatory reboots required for pagefile activation.

Design goals are therefore:

Support both v5 and v6 VM SKUs
Detect classic temp disks and new NVMe disks
Automatically initialize and format RAW disks
Recreate the temp disk after VM deallocation or scaling
Fall back safely to C: if no temp disk is available (e.g. SKU Change from Standard_E8ds_v6 to Standard_E8s_v6 )
Prevent infinite reboot loops
Provide detailed logging for troubleshooting

⚠️ Prevent race conditions with the AVD agent

This point is critical and often underestimated: the Azure Virtual Desktop services (RDAgent and RDAgentBootLoader) start early in the Windows boot process. If these services become available before the pagefile is fully configured and activated, user logins may already be accepted. These sessions are then established successfully, only to be immediately disconnected or logged out once the mandatory reboot for pagefile activation occurs.

A correct AVD pagefile solution must therefore ensure: No user logins are possible before pagefile configuration is finished!

Script Overview

This script provides a pagefile configuration mechanism and can be accessed in the repository below.

🧬 azure-avd-pagefile-automation

High-Level Workflow

Race Condition Protection
• Prevents AVD user logins before pagefile configuration is completed
• Stops AVD services during configuration
Detect Temp Disk
Supports both Azure temp disk types
• v5 SKUs: Msft Virtual Disk
• v6 SKUs: Microsoft NVMe Direct Disk v2
Disk Initialization
• Detects whether the temp disk is already usable
• Automatically initializes disk if required
• Removes CD-ROM drive letter (D:) if present
• Initializes disk using GPT
• Formats disk as NTFS
• Creates and mounts the D: drive
Pagefile Configuration
• Automatically configures pagefile on D: (preferred when temp disk is available)
• C: (fallback if no temp disk exists)
Safe Reboot Handling
• Detects when a reboot is required to activate the pagefile
• Uses registry-based tracking to prevent infinite reboot loops
• Resume configuration after restart
Disk Wipe Detection & Self-Healing
• Detects temp disk loss after VM deallocation or Host maintenance
• Reinitializes the disk and configures pagefile
Finalization
• Starts services only when the system is fully ready.
• Cleans up all registry markers after successful completion.

Pagefile Configuration Modes

The script supports two models.

System-managed (recommended)

$UseManagedPagefile = $true

1	$UseManagedPagefile = $true

Windows dynamically adjusts the pagefile size based on workload demands. This approach is generally considered the best option for multi-session Azure Virtual Desktop environments and has also been confirmed through analysis by GO-EUC.

Fixed size (optional)

$UseManagedPagefile = $false
$FixedInitialSizeMB = 16384
$FixedMaxSizeMB     = 32768

$UseManagedPagefile = $false

$FixedInitialSizeMB = 16384

$FixedMaxSizeMB = 32768

Useful when enforcing strict memory limits.

Automatic fallback logic

The most critical feature is fallback protection.

If the VM boots and:

The temp disk does not exist
D: is missing
The NVMe disk is not present

The script automatically:

Switches pagefile back to C:
Keeps the session host online
Avoids failed logins

Once the temp disk reappears (after redeploy or scaling):

D: is reinitialized
Pagefile is moved back automatically

No manual intervention required.

Reboot loop protection

Because pagefile changes require a reboot, the script includes:

$MaxRebootAttempts = 3

1	$MaxRebootAttempts = 3

State is tracked via registry:

HKLM:\SOFTWARE\AVD\AVDPagefileSetup

1	HKLM:\SOFTWARE\AVD\AVDPagefileSetup

This prevents:

Endless reboot cycles
Broken scaling operations
Hosts stuck in “Unavailable” state

If the limit is reached, the system safely exits and brings AVD services back online.

Logging and troubleshooting

All operations are logged to:

C:\Windows\Temp\AVDPagefileSetup\avd_nvme_pagefile.log

1	C:\Windows\Temp\AVDPagefileSetup\avd_nvme_pagefile.log

You get full visibility into:

Disk detection
Formatting
Pagefile changes
Reboot attempts
Fallback decisions

This makes root-cause analysis extremely easy when troubleshooting session host behavior.

Example – Log File Output:

[2026-01-27 23:30:26] === Script Start === Marker:  | RebootCount: 0
[2026-01-27 23:30:26] Checking 'CSECompleted' registry value existence...
[2026-01-27 23:30:26] 'CSECompleted' registry value exists.
[2026-01-27 23:30:27] Current pagefile state: D: NONE | C: NONE
[2026-01-27 23:30:33] Configuration needed: Temp disk available but D: drive not initialized
[2026-01-27 23:31:11] Stopped RDAgent and set startup to Manual
[2026-01-27 23:31:11] Stopped RDAgentBootLoader and set startup to Manual
[2026-01-27 23:31:12] CD-ROM detected on D:, removing drive letter
[2026-01-27 23:31:12] Removed D: from CD-ROM
[2026-01-27 23:31:14] Found temp disk: Disk 1
[2026-01-27 23:31:14] Initializing temp disk as GPT
[2026-01-27 23:31:14] Creating partition and formatting as D:
[2026-01-27 23:31:18] Temp disk initialized and formatted as D:
[2026-01-27 23:31:18] D: drive verified and accessible
[2026-01-27 23:31:18] Target drive D: exists: True
[2026-01-27 23:31:18] Pagefile file on D: exists: False
[2026-01-27 23:31:18] Configuration needed: True | Reboot needed: True
[2026-01-27 23:31:18] Configuring pagefile on D:
[2026-01-27 23:31:18] Setting system-managed pagefile on D:
[2026-01-27 23:31:18] Pagefile registry updated successfully
[2026-01-27 23:31:18] Reboot attempt #1 of 3
[2026-01-27 23:31:18] Initiating system reboot to activate pagefile on D:
[2026-01-27 23:31:53] === Script Start === Marker: 1 | RebootCount: 1
[2026-01-27 23:31:53] Checking 'CSECompleted' registry value existence...
[2026-01-27 23:31:53] 'CSECompleted' registry value exists.
[2026-01-27 23:31:53] Current pagefile state: D: EXISTS | C: NONE
[2026-01-27 23:31:55] D: drive with temp disk detected and pagefile is configured
[2026-01-27 23:31:55] Pagefile configuration is already optimal. Ensuring services are running.
[2026-01-27 23:31:55] Started service RDAgent
[2026-01-27 23:31:56] Started service RDAgentBootLoader
[2026-01-27 23:31:56] === Setup Complete === AVD Session Host ready for connections

[2026-01-27 23:30:26] === Script Start === Marker: | RebootCount: 0

[2026-01-27 23:30:26] Checking 'CSECompleted' registry value existence...

[2026-01-27 23:30:26] 'CSECompleted' registry value exists.

[2026-01-27 23:30:27] Current pagefile state: D: NONE | C: NONE

[2026-01-27 23:30:33] Configuration needed: Temp disk available but D: drive not initialized

[2026-01-27 23:31:11] Stopped RDAgent and set startup to Manual

[2026-01-27 23:31:11] Stopped RDAgentBootLoader and set startup to Manual

[2026-01-27 23:31:12] CD-ROM detected on D:, removing drive letter

[2026-01-27 23:31:12] Removed D: from CD-ROM

[2026-01-27 23:31:14] Found temp disk: Disk 1

[2026-01-27 23:31:14] Initializing temp disk as GPT

[2026-01-27 23:31:14] Creating partition and formatting as D:

[2026-01-27 23:31:18] Temp disk initialized and formatted as D:

[2026-01-27 23:31:18] D: drive verified and accessible

[2026-01-27 23:31:18] Target drive D: exists: True

[2026-01-27 23:31:18] Pagefile file on D: exists: False

[2026-01-27 23:31:18] Configuration needed: True | Reboot needed: True

[2026-01-27 23:31:18] Configuring pagefile on D:

[2026-01-27 23:31:18] Setting system-managed pagefile on D:

[2026-01-27 23:31:18] Pagefile registry updated successfully

[2026-01-27 23:31:18] Reboot attempt #1 of 3

[2026-01-27 23:31:18] Initiating system reboot to activate pagefile on D:

[2026-01-27 23:31:53] === Script Start === Marker: 1 | RebootCount: 1

[2026-01-27 23:31:53] Checking 'CSECompleted' registry value existence...

[2026-01-27 23:31:53] 'CSECompleted' registry value exists.

[2026-01-27 23:31:53] Current pagefile state: D: EXISTS | C: NONE

[2026-01-27 23:31:55] D: drive with temp disk detected and pagefile is configured

[2026-01-27 23:31:55] Pagefile configuration is already optimal. Ensuring services are running.

[2026-01-27 23:31:55] Started service RDAgent

[2026-01-27 23:31:56] Started service RDAgentBootLoader

[2026-01-27 23:31:56] === Setup Complete === AVD Session Host ready for connections

Integration

To ensure reliable operation, the pagefile script must run at every system startup. For these reason, the script must not be executed only once during image creation or through a Custom Script Extension during virtual machine provisioning. It must instead run automatically at every system startup to ensure consistent and reliable pagefile configuration The recommended approach is to use a Windows Scheduled Task triggered at startup.

Integration with Packer

Copy the script into the image

provisioner "file" {
  sources = [
    "scripts/900_Finalize/Set-Pagefile.ps1"
  ]
  destination = "C:/PackerBuild/"
}

provisioner "file" {

sources = [

"scripts/900_Finalize/Set-Pagefile.ps1"

]

destination = "C:/PackerBuild/"

}

2. Create a scheduled startup task

provisioner "powershell" {
  inline = [
    "$action = New-ScheduledTaskAction -Execute 'PowerShell.exe' -Argument '-NoProfile -ExecutionPolicy Bypass -File C:\\PackerBuild\\Set-Pagefile.ps1'",
    "$trigger = New-ScheduledTaskTrigger -AtStartup",
    "$principal = New-ScheduledTaskPrincipal -UserId 'SYSTEM' -RunLevel Highest",
    "$settings = New-ScheduledTaskSettingsSet -StartWhenAvailable",
    "Register-ScheduledTask -TaskName 'Packer-SetPagefile' -Action $action -Trigger $trigger -Principal $principal -Settings $settings -Force"
  ]
}

provisioner "powershell" {

inline = [

"$action = New-ScheduledTaskAction -Execute 'PowerShell.exe' -Argument '-NoProfile -ExecutionPolicy Bypass -File C:\\PackerBuild\\Set-Pagefile.ps1'",

"$trigger = New-ScheduledTaskTrigger -AtStartup",

"$principal = New-ScheduledTaskPrincipal -UserId 'SYSTEM' -RunLevel Highest",

"$settings = New-ScheduledTaskSettingsSet -StartWhenAvailable",

"Register-ScheduledTask -TaskName 'Packer-SetPagefile' -Action $action -Trigger $trigger -Principal $principal -Settings $settings -Force"

]

}

Custom Script Extension Dependency

In many Azure Virtual Desktop deployments, virtual machines are provisioned using Terraform or Bicep and finalized using an Azure Custom Script Extension (CSE). Typical tasks executed by the CSE include:

Installation and onboarding of antivirus or EDR agents
Monitoring and management agents
Product activation
Final system configuration steps

These actions are usually required before the session host becomes operational.

Why this matters for pagefile configuration

Because the Custom Script Extension runs during VM provisioning, it introduces an important dependency:

The pagefile script must not start while the CSE is still running.

Running the pagefile configuration in parallel with the Custom Script Extension can cause multiple issues:

Competing reboots
Failed agent registrations
Partially applied system settings

In worst cases, the VM may end up in an inconsistent provisioning state.

For that reason, the pagefile automation must only run after all CSE-based configuration tasks have completed successfully.

How this dependency is handled

To ensure correct execution order, the script includes an explicit CSE completion check. If CSE is not used in your environment, this section of the script can be removed without impact.

# =========================
# CSE Check (Azure Custom Script Extension)
# =========================
$CseRegPath = "HKLM:\SOFTWARE\AVD\CSE"
$CseRegName = "CSECompleted"

Write-Log "Checking '$($CseRegName)' registry value existence..."

if (-not (Get-ItemProperty -Path $CseRegPath -Name $CseRegName -ErrorAction SilentlyContinue)) {
    Write-Log "'$($CseRegName)' registry value does not exist. Exiting."
    exit 0
}

# =========================

# CSE Check (Azure Custom Script Extension)

# =========================

$CseRegPath = "HKLM:\SOFTWARE\AVD\CSE"

$CseRegName = "CSECompleted"

Write-Log "Checking '$($CseRegName)' registry value existence..."

if (-not (Get-ItemProperty -Path $CseRegPath -Name $CseRegName -ErrorAction SilentlyContinue)) {

Write-Log "'$($CseRegName)' registry value does not exist. Exiting."

exit 0

}

The logic verifies the presence of a dedicated registry value that is written by the Custom Script Extension once all provisioning tasks are finished. Only when this registry key exists does the pagefile script continue execution.

If the value is not found:

The script exits gracefully
No disk changes are made
No reboot is triggered

This guarantees that:

Terraform or Bicep provisioning completes cleanly
All agents are installed and activated first
Pagefile configuration runs only on a fully prepared system

Why the Custom Script Extension cannot be used alone

You might be wondering when implementing this script:

Why not simply use an Azure Custom Script Extension instead of a scheduled task?

The reason is straightforward but very important. The Custom Script Extension is executed only once, during the initial provisioning of the virtual machine.

After that:

it is not triggered again on reboot
it does not run after deallocation
it does not run when scaling plans start a VM
it does not react to temp disk wipes

This behavior makes the Custom Script Extension unsuitable for managing components that are not persistent, such as the Azure temp disk. As a result, the VM may boot without a valid pagefile, leading to login instability and performance issues.

Final Thoughts

I hope this article helps anyone who is currently onboarding or migrating Azure Virtual Desktop environments to v6 VM SKUs and wants to achieve a faster and smoother onramp.

The move to NVMe-based temp disks brings clear performance advantages, but it also introduces fundamental behavioral changes compared to previous VM generations. Unfortunately, Azure currently does not provide a built-in mechanism to automatically initialize these disks or handle pagefile placement in a reliable way.

As a result, customers are left to implement their own automation and safeguards, especially for scenarios involving multi-session workloads, scaling plans, and frequent deallocation events.

While this can be somewhat frustrating, understanding these changes and designing around them is essential for building stable AVD environments on v6 SKUs. Once properly automated, the platform performs extremely well and benefits significantly from the new NVMe architecture.

If you have ideas for improvement, find edge cases, or want to enhance the script further, feel free to reach out to me directly or submit a pull request on GitHub. Contributions, feedback, and real-world experiences are always welcome.