Azure Stack Hub, Microsoft’s hybrid cloud solution, allows organizations to apply Azure cloud services and capabilities directly in on-premises environments. A crucial aspect of managing Azure Stack Hub is the ability to add nodes should you need additional capacity.
Adding Scale Unit Devices
Increase the capacity of your Azure Stack Hub integrated systems by adding scale unit nodes. A scale unit in Azure Stack Hub is a collection of physical servers (nodes) that contribute to the overall resources offered in Azure Stack Hub. There are certain steps to follow:
- Step 1 – Prepare The Node: The first step requires you to power on the node and set up the Hardware Lifecycle Host (HLH). The HLH is a physical server that accompanies your Azure Stack Hub system, which hosts tools for managing the lifecycle of the system’s physical hardware.
- Step 2 – Install The Azure Stack Hub Package On The Node: Download the OEM package from the Azure Stack Hub download center, then copy and install it on the new node.
- Step 3 – Add The Node: Once the package is installed, use the Privileged Endpoint (PEP) to add the node to your existing scale unit.
For step 3, you could use the following PowerShell command:
Invoke-Command -Session $PEPsession -ScriptBlock {Add-AzsScaleUnitNode -Location local -ScaleUnitName "scaleunit01" -BmcCredential (Get-Credential) -BmcAddress "10.0.0.200" -TpmPresent:$true}
In this example, ‘scaleunit01’ represents the name of the scale unit to which you’re adding the node. The ‘BmcCredential’ and ‘BmcAddress’ parameters correspond to the credentials and IP address of the Baseboard Management Controller (BMC) on the node.
Considerations When Adding Nodes
- Time Frame: Adding a node may take several hours, up to an entire day.
- Compatibility: Before adding a node, ensure it’s compatible with existing hardware and software.
- Restarts: Adding nodes may require a reboot of the newly added node but it doesn’t affect the current running workloads.
- Availability Set: If you’ve distributed your App Service among availability sets, remember that each can contain a different number of fault domains.
| Availability Set | Supports Fault Domains |
|---|---|
| 2-node | Up to 2 |
| 4-node | Up to 20 |
| 8-node | Up to 4 |
| 12-node | Up to 4 |
| 16-node | Up to 4 |
Recovery After Adding Nodes
Once you add nodes and your system is updated, ensure that you run Test-AzureStack (in PowerShell) to verify the health of your Azure Stack Hub environment.
In summary, adding nodes to Azure Stack Hub isn’t an everyday task, but it’s a critical one when it’s time to expand capacity. It’s equally crucial for IT professionals preparing for the AZ-600 Configuring and Operating a Hybrid Cloud with Microsoft Azure Stack Hub exam to understand this process thoroughly, including the need for associated considerations and running of health checks once the nodes are added. Remember to study this and related topics comprehensively as you prepare for your certification exam.
Practice Test
True or False: You can add nodes to an Azure Stack Hub scale unit.
- True
- False
Answer: True.
Explanation: You can definitely add nodes to an Azure Stack Hub scale unit. This will help increase capacity as well as improve redundancy.
For Azure Stack to function correctly, is it necessary to have identical hardware in each node?
- True
- False
Answer: True.
Explanation: Yes, all nodes within a scale unit should have identical hardware to maintain performance and avoid potential hardware compatibility issues.
What type of node is recommended to add to Azure Stack to increase capacity?
- A. Storage node.
- B. Network node.
- C. Compute node.
- D. Database node.
Answer: C. Compute node.
Explanation: Compute nodes are added to increase capacity and assist in managing virtual machine instances.
True or False: It’s not possible to add a node to Azure Stack Hub when the hardware model doesn’t match the existing nodes.
- True
- False
Answer: True.
Explanation: Microsoft specifies that all nodes within a scale unit must be identical for Azure Stack to function as expected.
Which of the following scenarios may require the addition of a new node to Azure Stack Hub?
- A. Increasing services capacity.
- B. Replacing a failed node.
- C. Upgrading scale unit hardware.
- D. All of the above.
Answer: D. All of the above.
Explanation: All of these scenarios may warrant the addition of new nodes to Azure Stack hub to ensure the continued functionality and capacity of the system.
How many nodes can you add simultaneously to a scale unit?
- A. 1
- B. 2
- C. 3
- D. Any number
Answer: A. 1
Explanation: Only a single node can be added at a time to ensure stability and performance as the scale unit is updated.
True or False: When adding nodes, you should always maintain the node’s hardware lifecycle status.
- True
- False
Answer: True.
Explanation: The lifecycle status of a node is important to maintain when adding nodes, to ensure the system is kept healthy and operating effectively.
What is the first step in adding a node to the Azure Stack Hub?
- A. Configure the new hardware.
- B. Add the new hardware to the portal.
- C. Run the pre-validation check.
- D. Run remediation procedures.
Answer: A. Configure the new hardware.
Explanation: The first step in adding a node is to configure the new hardware, ensuring it is properly set up to be integrated with the existing system.
Which of the following roles is responsible for adding nodes to Azure Stack Hub?
- A. Azure Stack Operator.
- B. Azure Stack user.
- C. Developer.
- D. Cloud Administrator.
Answer: A. Azure Stack Operator.
Explanation: The Azure Stack Operator role is responsible for tasks such as adding nodes to Azure Stack Hub.
True or False: When adding nodes, it is recommended to validate user permissions.
- True
- False
Answer: True.
Explanation: Validating user permissions is important in maintaining security and correct functionality of the added node.
Which of the following volumes can be extended when adding additional nodes?
- A. Data.
- B. Recovery.
- C. Updates.
- D. All of the above.
Answer: D. All of the above.
Explanation: Data, recovery, and updates volumes can be extended when new nodes are added to provide additional storage and resiliency.
True or False: There is no need to run a system health check after adding a new node.
- True
- False
Answer: False.
Explanation: Running a system health check after adding a new node helps identify and address potential issues at an early stage.
True or False: Adding a new node requires downtime for the Azure Stack hub.
- True
- False
Answer: False.
Explanation: Adding a new node in Azure Stack hub does not induce downtime as the process is designed to be non-disruptive.
Adding nodes can be done remotely without physical access to hardware.
- A. True
- B. False
Answer: A. True.
Explanation: Adding nodes to Azure Stack hub is a process that can be handled remotely without the need for physical access to the hardware.
Can you add nodes to Azure Stack Development Kit (ASDK)?
- A. Yes.
- B. No.
Answer: B. No.
Explanation: Azure Stack Development Kit (ASDK) is a single-node version of Azure Stack Hub used for development. You cannot add nodes to it.
Interview Questions
Q: What is a node in Azure Stack Hub?
A: In Azure Stack Hub, a node refers to a single server machine in the Azure Stack Hub integrated system. It is a hardware component responsible for running the Azure services.
Q: What is the process for adding a node to an existing Azure Stack Hub scale unit?
A: To add a node to an existing Azure Stack Hub scale unit, you first need to contact your OEM hardware vendor and prepare the node according to their instructions. Once that’s done, you can add the node using the privileged endpoint (PEP).
Q: Does adding or removing nodes in Azure Stack Hub cause disruptions to running workloads?
A: When properly done, adding or removing nodes from Azure Stack Hub shouldn’t disrupt any running workloads. The Azure fabric ensures that it redistributes the workloads before node removal and redistributes them again after adding new nodes.
Q: How do you scale out an Azure Stack Hub multi-node integrated system?
A: Scaling out an Azure Stack Hub multi-node integrated system involves adding more nodes to the existing scale unit. It is done through the privileged endpoint and requires the new node to be prepared in line with the OEM vendor’s instructions.
Q: Can you remove a node immediately after adding it to Azure Stack Hub?
A: While technically feasible, it is not recommended to instantaneously remove a node right after adding it to Azure Stack Hub. The system requires time to redistribute the workloads properly across the nodes.
Q: Can you add nodes to Azure Stack Hub scale units if the system is in a degraded state?
A: No, you cannot add nodes to scale units in Azure Stack Hub if the system is in a degraded state. The system needs to be healthy before you can add nodes.
Q: What is the command used to add a node via Azure Stack Hub’s privileged endpoint?
A: The command used to add a node via Azure Stack Hub’s privileged endpoint is “Add-ScaleUnitNode.”
Q: Do you need to reboot the system after adding a node in Azure Stack Hub?
A: No, you do not need to reboot the system after adding a node in Azure Stack Hub. The new node should join the scale unit automatically.
Q: Are there any constraints to consider when adding a node to the Azure Stack Hub integrated system?
A: Yes, the node must meet the same hardware specifications as your existing nodes and you must have enough capacity on your network switches.
Q: Is it possible to add nodes of different sizes within the Azure Stack Hub?
A: No, all nodes within an Azure Stack Hub scale unit must be the same size and model as specified by the OEM hardware vendor.
Q: What verification step should be taken after adding a node to Azure Stack Hub?
A: After adding a node to Azure Stack Hub, it is essential to run the Test-AzureStack command to verify the health and status of the new addition.
Q: Can the addition of nodes in Azure Stack Hubs be automated?
A: While the Azure Stack Hub system does a significant amount of automatic resource distribution, the actual task of adding nodes is not automated and should be planned carefully.
Q: Can you add a node to a scale unit in Azure Stack Hub without contacting your OEM hardware vendor?
A: No, preparation of the new node is OEM-specific and you would need to follow the OEM-provided instructions to prepare the node before adding it.
Q: How long will it take for a newly added node to start running workloads in Azure Stack Hub?
A: Azure fabric will automatically begin redistributing workloads to the newly added node, but the timeframe can depend on various factors like the size of the workloads and the specifications of the node.
Q: How many nodes can be added to a scale unit in the Azure Stack Hub system?
A: The number of nodes that can be added to a scale unit in the Azure Stack Hub integrated system may depend on the specific architecture or model provided by the OEM.
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