Host Pool Architecture: Personal vs Pooled

Designing the compute layer

Resource organisation

Resource group strategies

Strategy	How it works	Best for
By host pool	One RG per host pool (containing VMs, NICs, disks, extensions)	Clear lifecycle management — delete the RG to clean up everything
By resource type	Separate RGs for networking, compute, storage, AVD objects	Teams with different RBAC responsibilities
By team/department	One RG per department (HR pool, Finance pool)	Organisations with departmental cost centres

Microsoft’s recommended pattern is by host pool — it keeps all related resources together and makes it simple to apply tags, policies, and RBAC at the RG level.

Subscription design

Pattern	When to use
Single subscription	Small to mid-size (under 2,000 session hosts). Simpler management.
Multi-subscription	Large enterprise, regulatory separation, blast-radius isolation. Separate subscriptions for production vs dev/test, or by region.

🏢 Raj at TerraStack: “We use three subscriptions: AVD-Production, AVD-Dev, and AVD-CAD. The CAD team burns through GPU quota fast, and we did not want that to affect the main production pool. Separate subscriptions give us separate Azure quotas.”

Management group hierarchy

Management groups let you apply Azure Policy and RBAC across multiple subscriptions:

• Root management group → Company-wide policies (e.g., allowed regions)
  • AVD management group → AVD-specific policies (e.g., required VM extensions, restricted VM sizes)
    • Production subscription
    • Dev/Test subscription
    • CAD subscription

🏛️ JC’s government structure: “Our Federal Department uses management groups to enforce data-residency policies. AVD session hosts MUST be in Australia East or Australia Southeast. The policy is applied at the management group level so nobody can accidentally create a host pool in a US region.”

Operating system choices

Decision shortcut:

• Default choice for pooled desktops: Windows 11 Enterprise multi-session
• Personal desktops for power users: Windows 11 Enterprise (single-session)
• Windows Server 2022 only when you have existing RDS CALs and do not want to buy Microsoft 365 or Windows E3/E5 licences

💡 Exam tip: Multi-session is unique to Azure

Windows 11 Enterprise multi-session is an Azure-only SKU. You CANNOT run it on-premises, on other clouds, or on Azure Local (except through Azure Virtual Desktop on Azure Local). If the exam asks “which OS supports multiple users on a single VM for AVD pooled desktops,” the answer is always Windows 11 Enterprise multi-session (or Windows 10 Enterprise multi-session for older deployments).

Host pool types

Pooled host pools

• Multiple users share session hosts
• Users get assigned to the least-loaded (or most-loaded) session host based on the load-balancing algorithm
• Two algorithms: breadth-first (spreads users evenly — best for performance) and depth-first (fills one VM before moving to the next — best for cost savings with autoscale)
• FSLogix profiles are required because users may land on a different VM each time

Personal host pools

• Each user is assigned a dedicated session host (1:1 mapping)
• Users always connect to the same VM
• Assignment can be direct (admin assigns a specific VM) or automatic (first-time connection assigns the next available VM)
• FSLogix is optional — the user’s profile persists on the local VM

Architecture patterns

Pattern	Description	Example
Shared departmental	One large pooled host pool for general knowledge workers	500-user HR and Finance pool
Dedicated team	Separate pooled pools per team for different configurations	Engineering pool with dev tools pre-installed
Personal for power users	Personal pool for users who need persistent customisation	CAD designers, data scientists
Dev/Test	Isolated pool for testing images and updates	Used with validation host pool feature

🌐 Priya at NomadTech: “Our 200 remote-first staff span 12 countries. We run two pooled host pools: one in West Europe for EMEA users and one in East US for Americas users. Ben (creative director) and five designers get personal desktops because they install custom Adobe plugins. Everyone else uses pooled.”

Personal desktop assignment

For personal host pools, you choose an assignment type:

Type	Behaviour	When to use
Automatic	First available unassigned VM is assigned on the user’s first connection	Simple — good default for most scenarios
Direct	Admin manually assigns a specific VM to a specific user	When you need to pre-configure or control which user gets which VM

To reassign a personal desktop (e.g., an employee leaves), you unassign the user from the session host in the portal or via PowerShell, then assign the new user. The VM retains its state — you may want to reimage it first.

ℹ️ Deep dive: Multi-personal desktop assignment

AVD now supports assigning a user to multiple personal desktops within the same host pool. This is useful when a single user needs different VM configurations — for example, one VM for standard work and another with GPU for design tasks. The LoadBalancerType for the host pool is set to MultiplePersistent. This is a newer feature that the exam may reference.

Validation host pools

A validation host pool receives AVD service updates before production pools. This gives you an early warning if an update breaks something.

• Mark any host pool as a validation pool in its properties
• Microsoft rolls out AVD agent and service updates to validation pools first
• Have a small group of testers use the validation pool daily
• If something breaks, you have time to report the issue before it hits production

🏢 Raj’s approach: “We have a 5-VM validation pool with 20 volunteer testers from IT. They run the same image as production. When an agent update caused a display driver issue last quarter, we caught it 48 hours before it hit the 8,000-user production pool.”

Azure Local for edge scenarios

Azure Local (formerly Azure Stack HCI) lets you run AVD session hosts on-premises. Use cases:

• Data residency — data must stay in a specific physical location
• Low-latency — branch offices with poor internet connectivity
• Regulated industries — healthcare or government requiring on-premises compute

Session hosts run on Azure Local hardware but are managed through the Azure portal, just like cloud-hosted VMs. Host pools can contain a mix of cloud and Azure Local session hosts.

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Next up: Now that you know the architecture, let’s size the VMs properly — Sizing for Performance and Capacity.