FusionAccess Service Provisioning · Topic 1 of 3
Service Encapsulation
Learn how a FusionAccess template VM is built and encapsulated: bare VM, OS, Tools, HDA, apps, OS tuning and Sysprep generalization before template use.
- 5 min
- Service encapsulation builds and generalizes the VM that all desktops are copied from.
- The order is bare VM, OS, Tools, HDA and applications, optimization, then encapsulation.
- Tools gives optimized drivers and VM status to FusionCompute; HDA lets the desktop register and accept HDP.
What it is
Service encapsulation is the preparation of the VM that every desktop will be copied from. The administrator builds one clean VM with the operating system, drivers, the HDA and the business applications, then encapsulates it so it can be safely copied many times.
Encapsulating means removing what must be unique to each machine, such as the computer name and the Windows security identifier (SID). The result is a generic image that is ready to become a template.
How it works
Step 1: create a bare VM
A bare VM is a VM with no operating system yet. It is created on FusionCompute with the CPU, memory, disk and NIC planned for the desktop, and connected to the service plane port group.
Size it for the users, not for the largest possible need. Every desktop made from it inherits these specifications, although they can be changed later.
Step 2: install the operating system
The OS ISO is mounted to the VM and the installation is done through the VM's VNC remote console in FusionCompute. A Windows desktop OS is the usual choice, and FusionAccess also supports Linux desktops.
For a full copy image the VM is not joined to the domain. Each full copy desktop joins later, after the image has been copied; linked clone templates differ, as the Template Creation page explains.
Step 3: install Tools
Tools is FusionCompute's VM driver package. It provides optimized paravirtualized disk and network drivers and lets FusionCompute read the VM's status.
Install it right after the OS. Without Tools, desktop disk and network performance are poor and some management functions do not work.
Step 4: install the HDA and applications
| Software | Purpose |
|---|---|
| HDA | Huawei Desktop Agent; registers the desktop with the HDC and serves the HDP connection |
| OS patches | Fix known vulnerabilities once, in the image, instead of on every desktop |
| Business applications | Office suite, line of business software, antivirus as the customer requires |
The HDA comes from the FusionAccess desktop installation image, with separate images for Windows and Linux desktops. A desktop without the HDA cannot register with the HDC, so users can never connect to it.
Step 5: optimize the operating system
| Optimization | Reason |
|---|---|
| Disable sleep and hibernation | A sleeping desktop stops answering the HDC and appears offline |
| Turn off unneeded services and visual effects | Saves CPU, memory and storage I/O across hundreds of desktops |
| Remove temporary files and caches | Keeps the image small and clean |
| Set the time zone and regional settings | Every copy inherits them |
Each small saving is multiplied by the number of desktops. A service using 1% CPU on one PC is significant across 1,000 VMs on shared hosts.
Step 6: encapsulate the VM
Encapsulation runs the FusionAccess template tool from the desktop installation image. For Windows full copy desktops it uses Microsoft Sysprep (System Preparation tool) to generalize the OS.
| Generalization removes | Why |
|---|---|
| The computer name | Each desktop gets its own name from the naming rule |
| The SID | Two domain members with the same SID cause conflicts |
| Machine specific settings | Each copy rebuilds them at first boot |
After encapsulation the VM shuts down. It must not be started again as a normal desktop, or it would personalize itself and lose its generic state.
Windows and Linux desktops
The process is the same in outline for both. Linux desktops use the Linux HDA package, and the steps that are specific to Windows, such as Sysprep, do not apply.
A worked example
A school prepares a classroom image. The administrator creates a bare VM with 2 vCPUs, 4 GB of memory and a 60 GB disk, installs Windows through the VNC console, then installs Tools and restarts.
She installs the HDA, an office suite and the school's teaching software, applies patches and disables sleep. Finally she runs the template tool to encapsulate the VM, which shuts down and is ready to become a template.
How the exam asks about this
- "Which operation must be performed when you create a Windows template for FusionAccess?" -> Encapsulating the template, which generalizes the OS.
- "Which component must be installed in the template VM so desktops can register with the HDC?" -> The HDA.
- "Why is Sysprep used for full copy desktops?" -> So each desktop made from the image gets a unique SID and computer name.
What to remember for the exam
- Service encapsulation builds and generalizes the VM that all desktops are copied from.
- The order is bare VM, OS, Tools, HDA and applications, optimization, then encapsulation.
- Tools gives optimized drivers and VM status to FusionCompute; HDA lets the desktop register and accept HDP.
- Disable sleep and trim services, because the image is multiplied across every desktop.
- Sysprep generalization removes the SID and computer name so copies do not conflict in the domain.
Do not start the encapsulated VM again before it becomes a template. Booting it completes setup, gives it a fixed identity and undoes the generalization.
Common mistakes
Joining the image to the domain before a full copy encapsulation. Each full copy desktop joins the domain on its own after it is created, with its own name.
Leaving out the HDA. The desktops start, but they never register with the HDC and users cannot reach them.
Skipping optimization. Sleep settings and idle services that are harmless on one PC cost real capacity and cause offline desktops at scale.
Check yourself
What does encapsulation remove from the template VM?
It removes machine specific identity such as the computer name and SID, so every desktop copied from it is unique.
Why is Tools installed in the template VM?
It provides optimized paravirtualized drivers and lets FusionCompute see the VM's status, which improves performance and management.
Why should sleep be disabled in the template VM?
A desktop that goes to sleep stops answering the HDC and appears unavailable to users.
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