Cloud Planning
Part of Cloud hosting and compute selection
Virtual machines versus managed application hosting
Compare VMs and managed application hosting by OS control, application compatibility, scaling and operating responsibility.
Choose a virtual machine when an application needs guest operating system control or software a managed platform cannot support. Choose managed application hosting when the application fits the platform’s rules and the team wants fewer server components to operate. Check those rules against the application before deciding.
What control changes hands?
On a VM, the customer manages the guest operating system and installed software, including updates, access, configuration and application deployment. A configured scaling group can adjust instance numbers and replace instances it judges unhealthy. It does not take over guest operating system maintenance or establish that the application scales correctly.
Managed application hosting shifts more underlying platform work to the provider. The team still manages application code, data, access settings, and the deployment and recovery work assigned to it under the chosen service. The exact division varies by product and plan.
| Question | Virtual machine | Managed application hosting |
|---|---|---|
| Can the team change the guest OS? | Generally within the VM operating model | Usually restricted or unavailable |
| Who plans guest OS updates? | The customer | The provider operates more of the platform; check the service terms |
| Where does persistent application data live? | On a managed disk or external data service chosen for the application | Check the platform’s storage rules; local instance files may disappear |
| How does capacity change? | Configure VM capacity and any scaling system | Configure the platform’s plan or scaling settings |
The table describes a decision pattern, not a promise about every product.
Control and Responsibility: Virtual Machines vs Managed Application Hosting
- Can the team change the guest OS?
- Generally within the VM operating model
- Who plans guest OS updates?
- The customer
- Where does persistent application data live?
- On a managed disk or external data service chosen for the application
- How does capacity change?
- Configure VM capacity and any scaling system
- Can the team change the guest OS?
- Usually restricted or unavailable
- Who plans guest OS updates?
- The provider operates more of the platform; check the service terms
- Where does persistent application data live?
- Check the platform’s storage rules; local instance files may disappear
- How does capacity change?
- Configure the platform’s plan or scaling settings
Check the application contract
List requirements that could rule out a managed platform: a particular operating system feature, privileged host access, a long-running process, local stateful files, a custom runtime component or a request that could exceed the platform’s time limit. Check each requirement against the exact service documentation.
For example, Azure App Service does not give applications access to its host operating system, although container access differs from host access. Cloud Run services have configurable request timeouts and disposable container file systems. These are limits of those products, not universal managed-hosting rules. A job or worker service may be a better fit for work outside a web request.
Compare effort with flexibility
A virtual machine can preserve a familiar software arrangement, along with the work of maintaining it. Name the owner for images, operating system updates, credentials, monitoring and recovery. Include that work in the decision.
Managed hosting can reduce infrastructure tasks, but an incompatible application may require code or deployment changes. Estimate those changes. Review supported runtimes, plan limits, network connections, data persistence and what happens when an instance is replaced or capacity scales down.
Pros and Cons: Virtual Machines vs Managed Application Hosting
- VM ProsFull control over guest OS, familiar software stack, predictable performance, supports legacy systems
- VM ConsHigher operational effort, requires managing updates, monitoring, backups, and security patches
- Managed Hosting ProsReduced infrastructure management, automatic scaling, built-in high availability, faster deployment cycles
- Managed Hosting ConsLimited OS access, potential need for code changes, platform-specific constraints (e.g. request timeouts, ephemeral storage)
Make a bounded choice
Check a representative application action on each viable configuration. Include a restart or replacement, a busy interval and required background work. Record the configuration, observations and remaining operator tasks. Until such a check is performed, compatibility and performance remain unverified.
If both models fit, compare total cost and operating responsibilities over the same period. A VM’s compute charge omits the team’s work; a dedicated managed plan may bill allocated capacity while the app is quiet. Choose a model the application fits and the team can operate.
Key Performance and Operational Metrics to Evaluate
- Restart or replacement impactVM: Manual recovery required; Managed: Automatic via platform health checks
- Busy interval handlingVM: Scaling must be manually configured; Managed: Auto-scales based on load
- Background work supportVM: Full support; Managed: Limited to job services (e.g., Azure Functions, Cloud Run Jobs)
- Total cost over timeVM: Compute + team effort; Managed: Allocated capacity costs even when idle
