Discovery, assessment, and dependency analysis - Common questions

This article answers common questions about discovery, assessment, and dependency analysis in Azure Migrate. If you have other questions, check these resources:

What geographies are supported for discovery and assessment with Azure Migrate?

Review the supported geographies for public and government clouds.

How many servers can I discover with an appliance?

You can discover up to 10,000 servers from VMware environment, up to 5,000 servers from Hyper-V environment, and up to 1000 physical servers by using a single appliance. If you have more servers, read about scaling a Hyper-V assessment, scaling a VMware assessment, or scaling a physical server assessment.

How do I choose the assessment type?

  • Use Azure VM assessments when you want to assess servers from your on-premises VMware and Hyper-V environment, and physical servers for migration to Azure VMs. Learn More
  • Use assessment type Azure SQL when you want to assess your on-premises SQL Server from your VMware environment for migration to Azure SQL Database or Azure SQL Managed Instance. Learn More
  • Use assessment type Azure App Service when you want to assess your on-premises ASP.NET web apps running on IIS web server from your VMware environment for migration to Azure App Service. Learn More
  • Use Azure VMware Solution (AVS) assessments when you want to assess your on-premises VMware VMs for migration to Azure VMware Solution (AVS) using this assessment type. Learn more
  • You can use a common group with VMware machines only to run both types of assessments. If you are running AVS assessments in Azure Migrate for the first time, it is advisable to create a new group of VMware machines.

Why is performance data missing for some/all servers in my Azure VM and/or AVS assessment report?

For "Performance-based" assessment, the assessment report export says 'PercentageOfCoresUtilizedMissing' or 'PercentageOfMemoryUtilizedMissing' when the Azure Migrate appliance cannot collect performance data for the on-premises servers. Check:

  • If the servers are powered on for the duration for which you are creating the assessment

  • If only memory counters are missing and you are trying to assess servers in Hyper-V environment. In this scenario, please enable dynamic memory on the servers and 'Recalculate' the assessment to reflect the latest changes. The appliance can collect memory utilization values for severs in Hyper-V environment only when the server has dynamic memory enabled.

  • If all of the performance counters are missing, ensure that outbound connections on ports 443 (HTTPS) are allowed.

    Note

    If any of the performance counters are missing, Azure Migrate: Server Assessment falls back to the allocated cores/memory on-premises and recommends a VM size accordingly.

Why is performance data missing for some/all SQL instances/databases in my Azure SQL assessment?

To ensure performance data is collected, please check:

  • If the SQL Servers are powered on for the duration for which you are creating the assessment
  • If the connection status of the SQL agent in Azure Migrate is 'Connected' and check the last heartbeat
  • If Azure Migrate connection status for all SQL instances is 'Connected' in the discovered SQL instance blade
  • If all of the performance counters are missing, ensure that outbound connections on ports 443 (HTTPS) are allowed

If any of the performance counters are missing, Azure SQL assessment recommends the smallest Azure SQL configuration for that instance/database.

Why confidence rating is not available for Azure App Service assessments?

Performance data is not captured for Azure App Service assessment and hence you do not see confidence rating for this assessment type. Azure App Service assessment takes configuration data of web apps in to account while performing assessment calculation.

Why is the confidence rating of my assessment low?

The confidence rating is calculated for "Performance-based" assessments based on the percentage of available data points needed to compute the assessment. Below are the reasons why an assessment could get a low confidence rating:

  • You did not profile your environment for the duration for which you are creating the assessment. For example, if you are creating an assessment with performance duration set to one week, you need to wait for at least a week after you start the discovery for all the data points to get collected. If you cannot wait for the duration, please change the performance duration to a smaller period and Recalculate the assessment.

  • Assessment is not able to collect the performance data for some or all the servers in the assessment period. For a high confidence rating, please ensure that:

    • Servers are powered on for the duration of the assessment
    • Outbound connections on ports 443 are allowed
    • For Hyper-V Servers dynamic memory is enabled
    • The connection status of agents in Azure Migrate are 'Connected' and check the last heartbeat
    • For Azure SQL assessments, Azure Migrate connection status for all SQL instances is "Connected" in the discovered SQL instance blade

    Please Recalculate the assessment to reflect the latest changes in confidence rating.

  • For Azure VM and AVS assessments, few servers were created after discovery had started. For example, if you are creating an assessment for the performance history of last one month, but few servers were created in the environment only a week ago. In this case, the performance data for the new servers will not be available for the entire duration and the confidence rating would be low. Learn more

  • For Azure SQL assessments, few SQL instances or databases were created after discovery had started. For example, if you are creating an assessment for the performance history of last one month, but few SQL instances or databases were created in the environment only a week ago. In this case, the performance data for the new servers will not be available for the entire duration and the confidence rating would be low. Learn more

The number of Azure VM or AVS assessments on the Discovery and assessment tool are incorrect

To remediate this, click on the total number of assessments to navigate to all the assessments and recalculate the Azure VM or AVS assessment. The discovery and assessment tool will then show the correct count for that assessment type.

I want to try out the new Azure SQL assessment

Discovery and assessment of SQL Server instances and databases running in your VMware environment is now in preview. Get started with this tutorial. If you want to try out this feature in an existing project, please ensure that you have completed the prerequisites in this article.

I want to try out the new Azure App Service assessment

Discovery and assessment of .NET web apps running in your VMware environment is now in preview. Get started with this tutorial. If you want to try out this feature in an existing project, please ensure that you have completed the prerequisites in this article.

I can't see some servers when I am creating an Azure SQL assessment

  • Azure SQL assessment can only be done on servers running where SQL instances were discovered. If you don't see the servers and SQL instances that you wish to assess, please wait for some time for the discovery to get completed and then create the assessment.
  • If you are not able to see a previously created group while creating the assessment, please remove any non-VMware server or any server without a SQL instance from the group.
  • If you are running Azure SQL assessments in Azure Migrate for the first time, it is advisable to create a new group of servers.

I can't see some servers when I am creating an Azure App Service assessment

  • Azure App Service assessment can only be done on servers running where web server role was discovered. If you don't see the servers that you wish to assess, please wait for some time for the discovery to get completed and then create the assessment.
  • If you are not able to see a previously created group while creating the assessment, please remove any non-VMware server or any server without a web app from the group.
  • If you are running Azure App Service assessments in Azure Migrate for the first time, it is advisable to create a new group of servers.

I want to understand how was the readiness for my instance computed?

The readiness for your SQL instances has been computed after doing a feature compatibility check with the targeted Azure SQL deployment type (Azure SQL Database or Azure SQL Managed Instance). Learn more

I want to understand how was the readiness for my web apps is computed?

The readiness for your web apps is computed by running series of technical checks to determine if your web app will run successfully in Azure App service or not. These checks are documented here.

Why is my web app marked as Ready with conditions or Not ready in my Azure App Service assessment?

This can happen when one or more technical checks fail for a given web app. You may click on the readiness status for the web app to find out details and remediation for failed checks.

Why is the readiness for all my SQL instances marked as unknown?

If your discovery was started recently and is still in progress, you might see the readiness for some or all SQL instances as unknown. We recommend that you wait for some time for the appliance to profile the environment and then recalculate the assessment. The SQL discovery is performed once every 24 hours and you might need to wait upto a day for the latest configuration changes to reflect.

Why is the readiness for some of my SQL instances marked as unknown?

This could happen if:

  • The discovery is still in progress. We recommend that you wait for some time for the appliance to profile the environment and then recalculate the assessment.
  • There are some discovery issues that you need to fix in the Errors and notifications blade.

The SQL discovery is performed once every 24 hours and you might need to wait upto a day for the latest configuration changes to reflect.

My assessment is in Outdated state

Azure VM/AVS assessment

If there are on-premises changes to servers that are in a group that's been assessed, the assessment is marked outdated. An assessment can be marked as “Outdated” because of one or more changes in below properties:

  • Number of processor cores
  • Allocated memory
  • Boot type or firmware
  • Operating system name, version and architecture
  • Number of disks
  • Number of network adaptor
  • Disk size change(GB Allocated)
  • Nic properties update. Example: Mac address changes, IP address addition etc.

Please Recalculate the assessment to reflect the latest changes in the assessment.

Azure SQL assessment

If there are changes to on-premises SQL instances and databases that are in a group that's been assessed, the assessment is marked outdated:

  • SQL instance was added or removed from a server
  • SQL database was added or removed from a SQL instance
  • Total database size in a SQL instance changed by more than 20%
  • Change in number of processor cores and/or allocated memory

Please Recalculate the assessment to reflect the latest changes in the assessment.

Azure Migrate recommends a specific Azure SQL deployment type that is compatible with your SQL instance. Migrating to a Microsoft recommended target reduces your overall migration effort. This Azure SQL configuration (SKU) has been recommended after considering the performance characteristics of your SQL instance and the databases it manages. If multiple Azure SQL configurations are eligible, we recommend the one, which is the most cost effective. Learn more

What deployment target should I choose if my SQL instance is ready for Azure SQL DB and Azure SQL MI?

If your instance is ready for both Azure SQL DB and Azure SQL MI, we recommend the target deployment type for which the estimated cost of Azure SQL configuration is lower.

Why is my instance marked as Potentially ready for Azure VM in my Azure SQL assessment?

This can happen when the target deployment type chosen in the assessment properties is Recommended and the SQL instance is not ready for Azure SQL Database and Azure SQL Managed Instance. The user is recommended to create an assessment in Azure migrate with assessment type as Azure VM to determine if the Server on which the instance is running is ready to migrate to an Azure VM. The user is recommended to create an assessment in Azure Migrate with assessment type as Azure VM to determine if the server on which the instance is running is ready to migrate to an Azure VM instead:

  • Azure VM assessments in Azure Migrate are currently lift-an-shift focused and will not consider the specific performance metrics for running SQL instances and databases on the Azure virtual machine.
  • When you run an Azure VM assessment on a server, the recommended size and cost estimates will be for all instances running on the server and can be migrated to an Azure VM using the Server Migration tool. Before you migrate, review the performance guidelines for SQL Server on Azure virtual machines.

I can't see some databases in my assessment even though the instance is part of the assessment

The Azure SQL assessment only includes databases that are in online status. In case the database is in any other status, the assessment ignores the readiness, sizing, and cost calculation for such databases. In case you wish you assess such databases, please change the status of the database and recalculate the assessment in some time.

I want to compare costs for running my SQL instances on Azure VM Vs Azure SQL Database/Azure SQL Managed Instance

You can create an assessment with type Azure VM on the same group that was used in your Azure SQL assessment. You can then compare the two reports side by side. Though, Azure VM assessments in Azure Migrate are currently lift-and-shift focused and will not consider the specific performance metrics for running SQL instances and databases on the Azure virtual machine. When you run an Azure VM assessment on a server, the recommended size and cost estimates will be for all instances running on the server and can be migrated to an Azure VM using the Server Migration tool. Before you migrate, review the performance guidelines for SQL Server on Azure virtual machines.

The storage cost in my Azure SQL assessment is zero

For Azure SQL Managed Instance, there is no storage cost added for the first 32 GB/instance/month storage and additional storage cost is added for storage in 32 GB increments. Learn More

I can't see some groups when I am creating an Azure VMware Solution (AVS) assessment

  • AVS assessment can be done on groups that have only VMware machines. Remove any non-VMware machine from the group if you intend to perform an AVS assessment.
  • If you are running AVS assessments in Azure Migrate for the first time, it is advisable to create a new group of VMware machines.

Queries regarding Ultra disks

Can I migrate my disks to Ultra disk using Azure Migrate?

No. Currently, both Azure Migrate and Azure Sire Recovery do not support migration to Ultra disks. Find steps to deploy Ultra disk here

Why are the provisioned IOPS and throughput in my Ultra disk more than my on-premises IOPS and throughput?

As per the official pricing page, Ultra Disk is billed based on the provisioned size, provisioned IOPS and provisioned throughput. As per an example provided:

If you provisioned a 200 GiB Ultra Disk, with 20,000 IOPS and 1,000 MB/second and deleted it after 20 hours, it will map to the disk size offer of 256 GiB and you'll be billed for the 256 GiB, 20,000 IOPS and 1,000 MB/second for 20 hours.

IOPS to be provisioned = (Throughput discovered) *1024/256

Does the Ultra disk recommendation consider latency?

No, currently only disk size, total throughput and total IOPS is used for sizing and costing.

This is possible as not all VM sizes that support Ultra disk are present in all Ultra disk supported regions. Change the target assessment region to get the VM size for this server.

I can't see some VM types and sizes in Azure Government

VM types and sizes supported for assessment and migration depend on availability in Azure Government location. You can review and compare VM types in Azure Government.

The size of my server changed. Can I run an assessment again?

The Azure Migrate appliance continuously collects information about the on-premises environment. An assessment is a point-in-time snapshot of on-premises servers. If you change the settings on a server that you want to assess, use the recalculate option to update the assessment with the latest changes.

How do I discover servers in a multitenant environment?

  • VMware: If an environment is shared across tenants and you don't want to discover a tenant's servers in another tenant's subscription, create VMware vCenter Server credentials that can access only the servers you want to discover. Then, use those credentials when you start discovery in the Azure Migrate appliance.
  • Hyper-V: Discovery uses Hyper-V host credentials. If servers share the same Hyper-V host, there's currently no way to separate the discovery.

Do I need vCenter Server?

Yes, Azure Migrate requires vCenter Server in a VMware environment to perform discovery. Azure Migrate doesn't support discovery of ESXi hosts that aren't managed by vCenter Server.

What are the sizing options in an Azure VM assessment?

With as-on-premises sizing, Azure Migrate doesn't consider server performance data for assessment. Azure Migrate assesses VM sizes based on the on-premises configuration. With performance-based sizing, sizing is based on utilization data.

For example, if an on-premises server has four cores and 8 GB of memory at 50% CPU utilization and 50% memory utilization:

  • As-on-premises sizing will recommend an Azure VM SKU that has four cores and 8 GB of memory.
  • Performance-based sizing will recommend a VM SKU that has two cores and 4 GB of memory because the utilization percentage is considered.

Similarly, disk sizing depends on sizing criteria and storage type:

  • If the sizing criteria is "performance-based" and the storage type is automatic, Azure Migrate takes the IOPS and throughput values of the disk into account when it identifies the target disk type (Standard, Premium or Ultra disk).
  • If the sizing criteria is "as on premises" and the storage type is Premium, Azure Migrate recommends a Premium disk SKU based on the size of the on-premises disk. The same logic is applied to disk sizing when the sizing is as-on-premises and the storage type is Standard, Premium or Ultra disk.

Does performance history and utilization affect sizing in an Azure VM assessment?

Yes, performance history and utilization affect sizing in an Azure VM assessment.

Performance history

For performance-based sizing only, Azure Migrate collects the performance history of on-premises machines, and then uses it to recommend the VM size and disk type in Azure:

  1. The appliance continuously profiles the on-premises environment to gather real-time utilization data every 20 seconds.
  2. The appliance rolls up the collected 20-second samples and uses them to create a single data point every 15 minutes.
  3. To create the data point, the appliance selects the peak value from all 20-second samples.
  4. The appliance sends the data point to Azure.

Utilization

When you create an assessment in Azure, depending on performance duration and the performance history percentile value that is set, Azure Migrate calculates the effective utilization value, and then uses it for sizing.

For example, if you set the performance duration to one day and the percentile value to 95th percentile, Azure Migrate sorts the 15-minute sample points sent by the collector for the past day in ascending order. It picks the 95th percentile value as the effective utilization.

Using the 95th percentile value ensures that outliers are ignored. Outliers might be included if your Azure Migrate uses the 99th percentile. To pick the peak usage for the period without missing any outliers, set Azure Migrate to use the 99th percentile.

How are import-based assessments different from assessments with discovery source as appliance?

Import-based Azure VM assessments are assessments created with machines that are imported into Azure Migrate using a CSV file. Only four fields are mandatory to import: Server name, cores, memory, and operating system. Here are some things to note:

  • The readiness criteria is less stringent in import-based assessments on the boot type parameter. If the boot type isn't provided, it is assumed the machine has BIOS boot type and the machine is not marked as Conditionally Ready. In assessments with discovery source as appliance, the readiness is marked as Conditionally Ready if the boot type is missing. This difference in readiness calculation is because users may not have all information on the machines in the early stages of migration planning when import-based assessments are done.
  • Performance-based import assessments use the utilization value provided by the user for right-sizing calculations. Since the utilization value is provided by the user, the Performance history and Percentile utilization options are disabled in the assessment properties. In assessments with discovery source as appliance, the chosen percentile value is picked from the performance data collected by the appliance.

Why is the suggested migration tool in import-based AVS assessment marked as unknown?

For machines imported via a CSV file, the default migration tool in an AVS assessment is unknown. Though, for VMware machines, it is recommended to use the VMware Hybrid Cloud Extension (HCX) solution. Learn More.

What is dependency visualization?

Dependency visualization can help you assess groups of servers to migrate with greater confidence. Dependency visualization cross-checks machine dependencies before you run an assessment. It helps ensure that nothing is left behind, and it helps avoid unexpected outages when you migrate to Azure. Azure Migrate uses the Service Map solution in Azure Monitor to enable dependency visualization. Learn more.

Note

Agent-based dependency analysis isn't available in Azure Government. You can use agentless dependency analysis

What's the difference between agent-based and agentless?

The differences between agentless visualization and agent-based visualization are summarized in the table.

Requirement Agentless Agent-based
Support This option is currently in preview, and is only available for servers in VMware environment. Review supported operating systems. In general availability (GA).
Agent No need to install agents on machines you want to cross-check. Agents to be installed on each on-premises machine that you want to analyze: The Microsoft Monitoring agent (MMA), and the Dependency agent.
Prerequisites Review the prerequisites and deployment requirements. Review the prerequisites and deployment requirements.
Log Analytics Not required. Azure Migrate uses the Service Map solution in Azure Monitor logs for dependency visualization. Learn more.
How it works Captures TCP connection data on machines enabled for dependency visualization. After discovery, it gathers data at intervals of five minutes. Service Map agents installed on a machine gather data about TCP processes and inbound/outbound connections for each process.
Data Source machine server name, process, application name.

Destination machine server name, process, application name, and port.
Source machine server name, process, application name.

Destination machine server name, process, application name, and port.

Number of connections, latency, and data transfer information are gathered and available for Log Analytics queries.
Visualization Dependency map of single server can be viewed over a duration of one hour to 30 days. Dependency map of a single server.

Map can be viewed over an hour only.

Dependency map of a group of servers.

Add and remove servers in a group from the map view.
Data export Last 30 days data can be downloaded in a CSV format. Data can be queried with Log Analytics.

Do I need to deploy the appliance for agentless dependency analysis?

Yes, the Azure Migrate appliance must be deployed.

Do I pay for dependency visualization?

No. Learn more about Azure Migrate pricing.

What do I install for agent-based dependency visualization?

To use agent-based dependency visualization, download and install agents on each on-premises machine that you want to evaluate:

You need these agents only if you use agent-based dependency visualization.

Can I use an existing workspace?

Yes, for agent-based dependency visualization you can attach an existing workspace to the migration project and use it for dependency visualization.

Can I export the dependency visualization report?

No, the dependency visualization report in agent-based visualization can't be exported. However, Azure Migrate uses Service Map, and you can use the Service Map REST API to retrieve the dependencies in JSON format.

Can I automate agent installation?

For agent-based dependency visualization:

What operating systems does MMA support?

Can I visualize dependencies for more than one hour?

For agent-based visualization, you can visualize dependencies for up to one hour. You can go back as far as one month to a specific date in history, but the maximum duration for visualization is one hour. For example, you can use the time duration in the dependency map to view dependencies for yesterday, but you can view dependencies only for a one-hour window. However, you can use Azure Monitor logs to query dependency data for a longer duration.

For agentless visualization, you can view the dependency map of a single server from a duration of between one hour and 30 days.

Can I visualize dependencies for groups of more than 10 servers?

You can visualize dependencies for groups that have up to 10 servers. If you have a group that has more than 10 servers, we recommend that you split the group into smaller groups, and then visualize the dependencies.

Next steps

Read the Azure Migrate overview.