Assess large numbers of servers in VMware environment for migration to Azure

This article describes how to assess large numbers (1000-35,000) of on-premises servers in a VMware environment for migration to Azure, using the Azure Migrate Discovery and assessment tool.

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This end-to-end VMware migration scenario documentation is currently in preview. For more information about using Azure Migrate, see the Azure Migrate product documentation.

Azure Migrate provides a hub of tools that help you to discover, assess, and migrate apps, infrastructure, and workloads to Microsoft Azure. The hub includes Azure Migrate tools, and partner independent software vendor (ISV) offerings.

In this article, you learn how to:

• Plan for assessment at scale.
• Configure Azure permissions and prepare VMware for assessment.
• Create an Azure Migrate project and create an assessment.
• Review the assessment as you plan for migration.

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If you want to try out a proof-of-concept to assess a couple of servers before assessing at scale, follow our tutorial series.

Plan for assessment

When you plan for assessment of large number of servers in VMware environment, there are a couple of things to think about:

• Plan Azure Migrate projects: Figure out how to deploy Azure Migrate projects. For example, if your data centers are in different geographies, or you need to store discovery, assessment, or migration-related metadata in a different geography, you might need multiple projects.
• Plan appliances: Azure Migrate uses an on-premises Azure Migrate appliance, deployed as a VMware VM, to continually discover servers. The appliance monitors environment changes such as adding servers, disks, or network adapters. It also sends metadata and performance data about them to Azure. You need to figure out how many appliances you need to deploy.
• Plan accounts for discovery: The Azure Migrate appliance uses an account with access to vCenter Server in order to discover servers for assessment and migration. If you're discovering more than 10,000 servers, set up multiple accounts as it is necessary that there's no overlap among servers discovered from any two appliances in a project.

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If you are setting up multiple appliances, ensure there is no overlap among the servers on the vCenter accounts provided. A discovery with such an overlap is an unsupported scenario. If a server is discovered by more than one appliance, this results in duplicates in discovery and in issues while enabling replication for the server using the Azure portal in the Migration and modernization tool.

Planning limits

Use the limits summarized in this table for planning.

Planning	Limits
Azure Migrate projects	Assess up to 35,000 servers in a project.
Azure Migrate appliance	An appliance can discover up to 10,000 servers on a vCenter Server. An appliance can connect to upto 10 vCenter Servers. An appliance can only be associated with a single Azure Migrate project. Any number of appliances can be associated with a single Azure Migrate project.
Group	You can add up to 35,000 servers in a single group.
Azure Migrate assessment	You can assess up to 35,000 servers in a single assessment.

With these limits in mind, here are some example deployments:

vCenter server	Servers to be discovered	Recommendation	Action
One	< 10,000	One Azure Migrate project. One appliance can discover up to 10,000 servers running on up to 10 vCenter Servers. Provide one or more vCenter Server accounts for discovery.	Set up an appliance to discover servers from up to 10 vCenter Servers mapped to one or more vCenter Server accounts, scoped to discover less than 10,000 servers. You can analyze dependencies on servers across vCenter Servers discovered from the same appliance.
One	> 10,000	One Azure Migrate project. One appliance can discover up to 10,000 servers running on up to 10 vCenter Servers. Provide one or more vCenter Server accounts for discovery.	Set up an appliance to connect up to 10 vCenter Servers mapped to one or more vCenter Server accounts, scoped to discover less than 10,000 servers. You need to deploy additional appliances for every 10,000 servers. If the number of servers is greater than 10,000, set up additional appliances with the vCenter Server accounts scoped accordingly. You can analyze dependencies on servers across vCenter Servers discovered from the same appliance. Ensure there's no overlap among the servers on the vCenter accounts provided. A discovery with such an overlap is an unsupported scenario. If a server is discovered by more than one appliance, this results in a duplicate in discovery and in issues while enabling replication for the server using the Azure portal in the Migration and modernization tool.
Multiple	< 10,000	One Azure Migrate project. One appliance can discover up to 10,000 servers running on up to 10 vCenter Servers. Provide one or more vCenter Server accounts for discovery.	Set up an appliance to connect up to 10 vCenter Servers mapped to one or more vCenter Server accounts, scoped to discover less than 10,000 servers. You need to deploy additional appliances for every 10 vCenter Servers. You can analyze dependencies on servers across vCenter Servers discovered from the same appliance.
Multiple	> 10,000	One Azure Migrate project. One appliance can discover up to 10,000 servers running on up to 10 vCenter Servers. Provide one or more vCenter Server accounts for discovery.	Set up an appliance to discover VMs from up to 10 vCenter Servers mapped to one or more vCenter Server accounts, scoped to discover less than 10,000 servers. You need to deploy additional appliances for every 10 vCenter Servers. If the number of servers is greater than 10,000, set up additional appliances with the vCenter Server accounts scoped accordingly. You can analyze dependencies on servers across vCenter Servers discovered from the same appliance. Ensure there's no overlap among the servers on the vCenter accounts provided. A discovery with such an overlap is an unsupported scenario. If a server is discovered by more than one appliance, this results in a duplicate in discovery and in issues while enabling replication for the server using the Azure portal in the Migration and modernization tool.

Plan discovery in a multitenant environment

If you're planning for a multitenant environment, you can scope the discovery on the vCenter Server.

• You can set the appliance discovery scope to a vCenter Server data centers, clusters, or folder of clusters, hosts or folder of hosts, or individual servers.
• If your environment is shared across tenants and you want to discover each tenant separately, you can scope access to the vCenter account that the appliance uses for discovery.
  • You might want to scope by VM folders if the tenants share hosts. Azure Migrate can't discover servers if the vCenter account has access granted at the vCenter VM folder level. If you're looking to scope your discovery by VM folders, you can do so by ensuring the vCenter account has read-only access assigned at a server level. Learn more.

Prepare for assessment

Prepare Azure and VMware for Discovery and assessment tool:

1. Verify VMware support requirements and limitations.
2. Set up permissions for your Azure account to interact with Azure Migrate.
3. Prepare VMware for assessment.

Follow the instructions in this tutorial to configure these settings.

Create a project

In accordance with your planning requirements, do the following:

1. Create an Azure Migrate projects.
2. Add the Azure Migrate Discovery and assessment tool to the projects.

Learn more about creating a project.

Create and review an assessment

1. Create assessments for servers in VMware environment.
2. Review the assessments in preparation for migration planning.

Follow the instructions in this tutorial to configure these settings.

Next steps

In this article, you:

• Planned to scale Azure Migrate assessments for servers in VMware environment
• Prepared Azure and VMware for assessment
• Created an Azure Migrate project and ran assessments
• Reviewed assessments in preparation for migration.

Now, learn how assessments are calculated, and how to modify assessments.