Best practices for creating assessments

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 third-party independent software vendor (ISV) offerings.

This article summarizes best practices when creating assessments using the Azure Migrate Server Assessment tool.

About assessments

Assessments you create with Azure Migrate Server Assessment are a point-in-time snapshot of data. There are two types of assessments you can create using Azure Migrate: Server Assessment:

Assessment Type Details
Azure VM Assessments to migrate your on-premises servers to Azure virtual machines.

You can assess your on-premises VMware VMs, Hyper-V VMs, and physical servers for migration to Azure using this assessment type. Learn more
Azure VMware Solution (AVS) Assessments to migrate your on-premises servers to Azure VMware Solution (AVS).

You can assess your on-premises VMware VMs for migration to Azure VMware Solution (AVS) using this assessment type. Learn more

Sizing criteria

Server Assessment provides two sizing criteria options:

Sizing criteria Details Data
Performance-based Assessments that make recommendations based on collected performance data Azure VM assessment: VM size recommendation is based on CPU and memory utilization data.

Disk type recommendation (standard HDD/SSD or premium-managed disks) is based on the IOPS and throughput of the on-premises disks.

Azure VMware Solution (AVS) assessment: AVS nodes recommendation is based on CPU and memory utilization data.
As-is on-premises Assessments that don't use performance data to make recommendations. Azure VM assessment: VM size recommendation is based on the on-premises VM size

The recommended disk type is based on what you select in the storage type setting for the assessment.

Azure VMware Solution (AVS) assessment: AVS nodes recommendation is based on the on-premises VM size.

Example

As an example, if you have an on-premises VM with four cores at 20% utilization, and memory of 8 GB with 10% utilization, the Azure VM assessment will be as follows:

  • Performance-based assessment:

    • Identifies effective cores and memory based on core (4 x 0.20 = 0.8), and memory (8 GB x 0.10 = 0.8) utilization.
    • Applies the comfort factor specified in assessment properties (let's say 1.3x) to get the values to be used for sizing.
    • Recommends the nearest VM size in Azure that can support ~1.04 cores (0.8 x 1.3) and ~1.04 GB (0.8 x 1.3) memory.
  • As-is (as on-premises) assessment:

    • Recommends a VM with four cores; 8 GB of memory.

Best practices for creating assessments

The Azure Migrate appliance continuously profiles your on-premises environment, and sends metadata and performance data to Azure. Follow these best practices for assessments of servers discovered using an appliance:

  • Create as-is assessments: You can create as-is assessments immediately once your machines show up in the Azure Migrate portal.
  • Create performance-based assessment: After setting up discovery, we recommend that you wait at least a day before running a performance-based assessment:
    • Collecting performance data takes time. Waiting at least a day ensures that there are enough performance data points before you run the assessment.
    • When you're running performance-based assessments, make sure you profile your environment for the assessment duration. For example, if you create an assessment with a performance duration set to one week, you need to wait for at least a week after you start discovery, for all the data points to be collected. If you don't, the assessment won't get a five-star rating.
  • Recalculate assessments: Since assessments are point-in-time snapshots, they aren't automatically updated with the latest data. To update an assessment with the latest data, you need to recalculate it.

Follow these best practices for assessments of servers imported into Azure Migrate via .CSV file:

  • Create as-is assessments: You can create as-is assessments immediately once your machines show up in the Azure Migrate portal.
  • Create performance-based assessment: This helps to get a better cost estimate, especially if you have overprovisioned server capacity on-premises. However, the accuracy of the performance-based assessment depends on the performance data specified by you for the servers.
  • Recalculate assessments: Since assessments are point-in-time snapshots, they aren't automatically updated with the latest data. To update an assessment with the latest imported data, you need to recalculate it.

FTT Sizing Parameters for AVS assessments

The storage engine used in AVS is vSAN. vSAN storage polices define storage requirements for your virtual machines. These policies guarantee the required level of service for your VMs because they determine how storage is allocated to the VM. These are the available FTT-Raid Combinations:

Failures to Tolerate (FTT) RAID Configuration Minimum Hosts Required Sizing consideration
1 RAID-1 (Mirroring) 3 A 100GB VM would consume 200GB.
1 RAID-5 (Erasure Coding) 4 A 100GB VM would consume 133.33GB
2 RAID-1 (Mirroring) 5 A 100GB VM would consume 300GB.
2 RAID-6 (Erasure Coding) 6 A 100GB VM would consume 150GB.
3 RAID-1 (Mirroring) 7 A 100GB VM would consume 400GB.

Best practices for confidence ratings

When you run performance-based assessments, a confidence rating from 1-star (lowest) to 5-star (highest) is awarded to the assessment. To use confidence ratings effectively:

  • Azure Migrate Server Assessment needs the utilization data for VM CPU/Memory.
  • For each disk attached to the on-premises VM, it needs the read/write IOPS/throughput data.
  • For each network adapter attached to the VM, it needs the network in/out data.

Depending on the percentage of data points available for the selected duration, the confidence rating for an assessment is provided as summarized in the following table.

Data point availability Confidence rating
0%-20% 1 Star
21%-40% 2 Star
41%-60% 3 Star
61%-80% 4 Star
81%-100% 5 Star

Common assessment issues

Here's how to address some common environment issues that affect assessments.

Out-of-sync assessments

If you add or remove machines from a group after you create an assessment, the assessment you created will be marked out-of-sync. Run the assessment again (Recalculate) to reflect the group changes.

Outdated assessments

If there are on-premises changes to VMs 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.

Run the assessment again (Recalculate) to reflect the changes.

Low confidence rating

An assessment might not have all the data points for a number of reasons:

  • You did not profile your environment for the duration for which you are creating the assessment. For example, if you are creating a performance-based 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. You can always click on Recalculate to see the latest applicable confidence rating. Confidence rating is applicable only when you create a performance-based assessment.

  • Few VMs were shut down during the period for which the assessment is calculated. If some VMs were powered off for some duration, Server Assessment will not be able to collect the performance data for that period.

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

Migration Tool Guidance for AVS assessments

In the Azure readiness report for Azure VMware Solution (AVS) assessment, you can see the following suggested tools:

  • VMware HCX or Enterprise: For VMware machines, VMware Hybrid Cloud Extension (HCX) solution is the suggested migration tool to migrate your on-premises workload to your Azure VMware Solution (AVS) private cloud. Learn More.
  • Unknown: For machines imported via a CSV file, the default migration tool is unknown. Though, for VMware machines, its is recommended to use the VMware Hybrid Cloud Extension (HCX) solution.

Next steps

  • Learn how assessments are calculated.
  • Learn how to customize an assessment.