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