Host Pool Options (Pooled and Personal)

This reference defines host pool behavior, parameter mapping, and recommended autoscale patterns.

1) Host pool types

Pooled

• Purpose: shared compute for task workers, call centers, and shift-based operations.
• Load balancing options:
  • BreadthFirst: spreads users across hosts.
  • DepthFirst: fills hosts before moving to next host.
• Recommended baseline:
  • BreadthFirst for user-experience consistency.
  • DepthFirst for cost-optimized autoscale scenarios.

Personal

• Purpose: dedicated VM per user for developers, engineers, privileged workflows.
• Assignment:
  • Automatic: first available VM assigned at first sign-in.
  • Direct: preassigned VM-to-user mapping by operations.
• Recommended baseline: Direct where strict ownership/compliance is needed.

2) Core parameter reference

Parameter	Scope	Applies To	Notes
hostPoolType	Host pool	Pooled/Personal	Pooled or Personal
loadBalancingType	Host pool	Pooled	BreadthFirst or DepthFirst
maxSessionLimit	Host pool	Pooled	Set from load-test data
personalDesktopAssignmentType	Host pool	Personal	Automatic or Direct
startVMOnConnect	Host pool	Both	Requires RBAC + service principal
registrationTokenExpiration	Host registration	Both	Short-lived token recommended

3) Configuration mapping

Canonical key (config/variables.yml)	Bicep	Terraform	PowerShell
host_pool.type	hostPoolType	host_pool_type	-HostPoolType
host_pool.load_balancing	loadBalancingType	load_balancing_type	-LoadBalancingType
host_pool.max_sessions	maxSessionLimit	max_session_limit	-MaxSessionLimit
host_pool.personal_assignment	personalDesktopAssignmentType	personal_desktop_assignment_type	-PersonalAssignmentType
host_pool.start_vm_on_connect	startVMOnConnect	start_vm_on_connect	-StartVMOnConnect

4) Implementation examples

Bicep (pooled):

param hostPoolType string = 'Pooled'
param loadBalancingType string = 'BreadthFirst'
param maxSessionLimit int = 12

resource hostPool 'Microsoft.DesktopVirtualization/hostPools@2024-04-03' = {
	name: 'hp-pooled-prod'
	location: resourceGroup().location
	properties: {
		hostPoolType: hostPoolType
		loadBalancerType: loadBalancingType
		maxSessionLimit: maxSessionLimit
		startVMOnConnect: true
		preferredAppGroupType: 'Desktop'
	}
}

Terraform (personal):

resource "azurerm_virtual_desktop_host_pool" "personal" {
	name                            = "hp-personal-prod"
	location                        = azurerm_resource_group.avd.location
	resource_group_name             = azurerm_resource_group.avd.name
	type                            = "Personal"
	personal_desktop_assignment_type = "Direct"
	start_vm_on_connect             = true
}

PowerShell:

New-AzWvdHostPool -ResourceGroupName $rg -Name 'hp-pooled-prod' -Location $location `
	-HostPoolType 'Pooled' -LoadBalancerType 'BreadthFirst' -MaxSessionLimit 12 -StartVMOnConnect:$true

5) Autoscale patterns

Schedule-first

• Start baseline capacity before business hours.
• Drain and stop non-required hosts after hours.

Load-first

• Increase hosts on session/cpu thresholds.
• Decrease hosts on sustained low utilization.

Hybrid

• Schedule baseline + dynamic headroom during peaks.

Recommended controls:

• Reserve at least one spare host per pool.
• Use drain mode before host maintenance.
• Keep scale actions idempotent and logged.

6) Start VM on Connect requirements

• App registration/service principal authorized on subscription/RG scope.
• Required roles: VM start permission, AVD host pool access.
• Validate startup latency with login SLA tests.

7) Operational checks

• Track session distribution by host and pool.
• Alert on host pools with registration or heartbeat drops.
• Review maxSessionLimit quarterly against real concurrency.

References

• AVD host pool overview: https://learn.microsoft.com/azure/virtual-desktop/host-pool-load-balancing
• Personal desktop assignment: https://learn.microsoft.com/azure/virtual-desktop/configure-host-pool-personal-desktop-assignment-type
• Autoscale for pooled host pools: https://learn.microsoft.com/azure/virtual-desktop/autoscale-scaling-plan
• Start VM on Connect: https://learn.microsoft.com/azure/virtual-desktop/start-virtual-machine-connect