top of page

Assess AWS instances for migration to Azure

Updated: May 16

As part of your migration journey to Azure, you assess your on-premises workloads to measure cloud readiness, identify risks, and estimate costs and complexity.

This blog shows you how to assess Amazon Web Services (AWS) instances for migration to Azure using the Azure Migrate: Discovery and Assessment tool.

In this blog, you learn how to:

  • Run an assessment based on server metadata and configuration information.

  • Run an assessment based on performance data.


  • Before you follow the steps in this tutorial, complete the first tutorial in this series to discover your on-premises inventory.

  • Make sure AWS instances aren't running Windows Server 2003 or SUSE Linux. Assessment isn't supported for these servers.

Decide which Assessment to run

Decide whether you want to run an assessment using sizing criteria based on server configuration data/metadata that's collected as-is on-premises or on dynamic performance data.




As-is on-premises

Assess based on server configuration data/metadata.

Recommended Azure VM size is based on the on-premises VM size. The recommended Azure disk type is based on what you select in the storage type setting in the Assessment.


Assess based on collected dynamic performance data.

Recommended Azure VM size is based on CPU and memory utilization data. The recommended disk type is based on the IOPS and throughput of the on-premises disks.

Run an assessment

Run an assessment as follows:

1. On the Overview page > Windows, Linux and SQL Server, click Assess and migrate servers.

Azure Migrate

2. In Azure Migrate: Discovery and Assessment, click Assess.

Azure Migrate: Discovery and assessment, click Assess.

3 . In Assess servers > Assessment type, select Azure VM.

4. In Discovery Source:

If you discovered servers using the appliance, select Servers discovered from Azure . Migrate appliance.

If you discovered servers using an imported CSV file, select Imported servers.

5. Click Edit to review the assessment properties.

Azure Migrate : Create assessment

6. In Assessment properties > Target Properties:

In the Target location, specify the Azure region you want to migrate to.

  • Size and cost recommendations are based on the location that you specify. Once you change the target location from default, you will be prompted to specify Reserved Instances and VM series.

  • In Azure Government, you can target assessments in these regions

In Storage type,

  • If you want to use performance-based data in the Assessment, select Automatic for Azure Migrate to recommend a storage type based on disk IOPS and throughput.

  • Alternatively, select the storage type you want to use for VM when you migrate it.

In Reserved Instances, specify whether you want to use reserve instances for the VM when you migrate it.

  • If you select to use a reserved instance, you can't specify 'Discount (%) or VM uptime.

  • Learn more

7. In VM Size:

In the Sizing criterion, select if you want to base the Assessment on server configuration data/metadata or on performance-based data. If you use performance data:

  • In Performance history, indicate the data duration on which you want to base the Assessment

  • In Percentile Utilization, specify the percentile value you want for the performance sample.

In VM Series, specify the Azure VM series you want to consider.

  • If you're using performance-based Assessment, Azure Migrate suggests a value for you.

  • Tweak settings as needed. For example, if you don't have a production environment that needs A-series VMs in Azure, you can exclude A-series from the series list.

In the Comfort factor, indicate the buffer you want to use during the Assessment. This accounts for issues like seasonal usage, short performance history, and likely increases in future usage. For example, if you use a comfort factor of two:


Effective utilization

Add comfort factor (2.0)





8 GB

16 GB

8. In Pricing:

In the offer, specify the Azure offer if you're enrolled. The Assessment estimates the cost for that offer.

In Currency, select the billing currency for your account.

In Discount (%), add any subscription-specific discounts you receive on top of the Azure offer. The default setting is 0%.

In VM Uptime, specify the duration (days per month/hour per day) that VMs will run.

  • This is useful for Azure VMs that won't run continuously.

  • Cost estimates are based on the duration specified.

  • The default is 31 days per month/24 hours per day.

In the EA Subscription, specify whether to take an Enterprise Agreement (EA) subscription discount into account for cost estimation.

In Azure Hybrid Benefit, specify whether you already have a Windows Server license. If you do, and they're covered with active Software Assurance of Windows Server Subscriptions: you can apply for the Azure Hybrid Benefit when you bring licenses to Azure.

9. Click Save if you make changes.

Assessment properties

10. In Assess Servers > click Next.

11. In Select servers to assess > Assessment name > specify a name for the Assessment.

12. In Select or Create a group > select Create New and specify a group name.

13. Select the appliance and the VMs you want to add to the group. Then click Next.

14. In Review + create an assessment, review the assessment details, and click Create Assessment to create the group and run the Assessment.

15. After the Assessment is created, view it in Servers > Azure Migrate: Discovery and Assessment> Assessments.

16. Click Export Assessment to download it as an Excel file.

Review an assessment

An assessment describes:

  • Azure readiness: Whether VMs are suitable for migration to Azure.

  • Monthly cost estimation: The estimated monthly compute and storage costs for running the VMs in Azure.

  • Monthly storage cost estimation: Estimated costs for disk storage after migration.

To view an assessment:

1. In Windows, Linux and SQL Server > Azure Migrate: Discovery and Assessment, click the number next to Assessments.

2. In Assessments, select an assessment to open it. As an example (estimations and costs , for example only):

Assessment Details

3. Review the assessment summary. You can also edit the assessment properties or recalculate the Assessment.

Review readiness

1. Click Azure readiness.

2. In Azure readiness, review the VM status:

Ready for Azure: Used when Azure Migrate recommends a VM size and cost estimates for VMs in the Assessment.

Ready with conditions: Shows issues and suggested remediation.

Not prepared for Azure: Shows issues and suggested remediation.

Readiness unknown: Used when Azure Migrate can't assess readiness because of data availability issues.

3. Select an Azure readiness status. You can view VM readiness details. You can also drill down to see VM details, including compute, storage, and network settings.

Review cost estimates

The assessment summary shows the estimated computing and storage costs for running VMs in Azure.

1. Review the monthly total costs. Costs are aggregated for all VMs in the assessed group.

Cost estimates are based on the size recommendations for a server, its disks, and its properties.

Estimated monthly costs for computing and storage are shown.

The cost estimation is for running the on-premises VMs on Azure VMs. The estimation doesn't consider PaaS or SaaS costs.

2. Review monthly storage costs. The view shows the aggregated storage costs for the assessed group, split over different storage disks.

3. You can drill down to see cost details for specific VMs.

Review confidence rating

Azure Migrate assigns a confidence rating to performance-based assessments. The rating ranges from one star (lowest) to five stars (highest).

The confidence rating helps you estimate the reliability of size recommendations in the Assessment. The rating is based on the availability of data points needed to compute the Assessment.

Confidence ratings are as follows.

Data point availability

Confidence rating


1 Star


2 Star


3 Star


4 Star


5 Star

7 views0 comments

Recent Posts

See All


bottom of page