Tutorial / Cram Notes
These operations enable administrators to maintain system health, update nodes, and manage resource allocation. Here we will explore the key node operations: start, stop, resume, repair, drain, and shutdown.
Starting a Node
When you start a node, you power it on and allow it to become part of the Azure Stack Hub infrastructure. Starting a node is usually part of the initial deployment or when bringing a node back into service after maintenance.
Example command to start a physical node via the BMC (Baseboard Management Controller):
Start-AzsScaleUnitNode -Name Node01
Stopping a Node
Stopping a node, not to be confused with shutting it down, simply means to gracefully stop all services without powering off the hardware. This might be done to perform certain maintenance tasks that do not require a hardware restart.
Example command to stop a node:
Stop-AzsScaleUnitNode -Name Node01
Resuming a Node
When a node has been paused or stopped for maintenance, the resume operation brings it back online, reconnecting it to the scale unit and allowing it to participate in the cluster activities.
Example command to resume a node:
Resume-AzsScaleUnitNode -Name Node01
Repairing a Node
Repair operations are performed when a node is experiencing issues. This can involve replacing failed components, updating firmware, or fixing software issues. Repairing a node typically involves taking it offline, performing the necessary operations, and then bringing it back into service.
Example command to repair a node:
Repair-AzsScaleUnitNode -Name Node01
Draining a Node
Before you carry out maintenance or updates, it’s best to drain a node. This involves moving running workloads to other nodes within the scale unit, ensuring minimal disruption. Once drained, the node can be safely stopped or shut down for maintenance.
Example command to drain a node:
Drain-AzsScaleUnitNode -Name Node01
Shutting Down a Node
Shutting down a node powers off the hardware. This is done when the node requires a physical intervention, such as hardware replacement or deep troubleshooting that cannot be done while the system is running.
Example command to shut down a node:
Stop-AzsScaleUnitNode -Name Node01 -Shutdown
Here’s a comparison of the primary node operations:
| Operation | Purpose | Behavioral Effect | Use Case |
|---|---|---|---|
| Start | Power on and bring node online | Node joins the cluster and becomes available for workloads | After scheduled maintenance or a planned downtime |
| Stop | Gracefully stop services | Services are stopped without powering off the hardware | Preparing a node for maintenance without hardware interaction |
| Resume | Bring a paused node back online | Node rejoins the cluster and resumes normal operations | To reactivate a node post-maintenance or after troubleshooting |
| Repair | Address issues with a node | Node is taken offline for repair and is brought back online afterwards | To fix software or hardware issues with the node |
| Drain | Relocate workloads from the node | Workloads are moved to other nodes, the node is then free for maintenance | Before maintenance to ensure workloads continue to run on other nodes |
| Shutdown | Power off the node hardware | The node is fully powered down and requires physical interaction to power back on | Deep maintenance activities that cannot be performed while the node is online |
These node operations allow Azure Stack Hub administrators to effectively manage the lifecycle and health of the system’s nodes. By utilizing these commands, administrators can ensure a smooth operation and minimal downtime for their Azure Stack Hub environment.
Practice Test with Explanation
True or False: To start a stopped node in Azure Stack Hub, you can use the Start-AzsScaleUnitNode cmdlet via PowerShell.
- Answer: True
The Start-AzsScaleUnitNode cmdlet is used to start a stopped node in your Azure Stack Hub scale unit.
True or False: The Azure Stack Hub portal provides an option to directly shut down an individual scale unit node.
- Answer: False
The Azure Stack Hub portal doesn’t provide an option to directly shut down an individual node. You have to use PowerShell or the privileged endpoint (PEP) for such operations.
When performing a node repair operation, which of the following steps should be taken? (Select all that apply)
- A) Evacuate all user and system workloads from the node
- B) Take a full backup of all VMs on the node
- C) Put the node into maintenance mode
- D) Reimage the node if necessary
Answer: A, C, D
Before repairing a node, you typically need to evacuate workloads, put the node into maintenance mode, and potentially reimage the node if that’s part of the repair process. Taking a full backup of all VMs is not a necessary step for a node repair but might be part of a broader disaster recovery plan.
True or False: It’s possible to drain a node in Azure Stack Hub without causing any downtime for the user workloads running on that node.
- Answer: True
Draining a node effectively moves workloads off that node to permit maintenance or repair, and Azure Stack Hub is designed to handle this with high availability to avoid downtime.
Which PowerShell cmdlet is used to stop a scale unit node in Azure Stack Hub?
- A) Stop-AzsScaleUnitNode
- B) Shutdown-AzsScaleUnitNode
- C) Disable-AzsScaleUnitNode
- D) Stop-AzureStackHubNode
Answer: A) Stop-AzsScaleUnitNode
The Stop-AzsScaleUnitNode cmdlet is used to stop a scale unit node in Azure Stack Hub for maintenance or troubleshooting purposes.
True or False: You can use the repair action to address hardware issues on an Azure Stack Hub node.
- Answer: True
The repair action can be used to address both hardware and software issues on an Azure Stack Hub node, depending on the nature of the problem.
Which of the following is the correct cmdlet to exit maintenance mode on a node in Azure Stack Hub?
- A) Resume-AzsScaleUnitNode
- B) Restart-AzsScaleUnitNode
- C) Enable-AzsScaleUnitNode
- D) Start-AzsScaleUnitNode
Answer: A) Resume-AzsScaleUnitNode
Resume-AzsScaleUnitNode is the cmdlet used to bring a node back online from maintenance mode.
True or False: When you shut down a node in Azure Stack Hub, you are also effectively shutting down all VMs hosted on that node.
- Answer: True
Shutting down a node will effectively stop all the Virtual Machines (VMs) hosted on that node unless they are live-migrated to another node before the shutdown if the infrastructure supports it.
What is the purpose of the drain action in Azure Stack Hub?
- A) To add additional resources to a node
- B) To remove a node from rotation for updates or maintenance
- C) To delete a node from the scale unit
- D) To redistribute workloads across existing nodes
Answer: B) To remove a node from rotation for updates or maintenance
The drain action is used to gracefully remove a node from rotation so it can be updated, maintained, or repaired without impacting the workloads.
True or False: After initiating a repair on an Azure Stack Hub node, you need to wait until manual checks are complete before proceeding with further operations.
- Answer: True
You should not proceed with further operations until the repair task has been completed and you have verified the state of the node manually.
Which condition must be met before shutting down an Azure Stack Hub node for maintenance?
- A) All other nodes must be in maintenance mode.
- B) The node must be drained of all workloads.
- C) The hardware lifecycle host must be offline.
- D) The storage spaces must be in a degraded state.
Answer: B) The node must be drained of all workloads.
Before shutting down a node for maintenance, it must be drained of all workloads to avoid service disruption.
True or False: You can resume all paused workloads on an Azure Stack Hub node using the Azure Stack Admin portal.
- Answer: False
You cannot resume workloads directly from the Azure Stack Admin portal. Resuming operations such as exiting maintenance mode is typically performed using PowerShell cmdlets.
Interview Questions
What are Azure Stack nodes?
Azure Stack nodes are physical servers that host virtual machines and services in an Azure Stack deployment.
What are some examples of node operations that can be performed in Azure Stack?
Examples of node operations in Azure Stack include start, stop, resume, repair, drain, and shutdown.
How can node operations be performed in Azure Stack?
Node operations in Azure Stack can be performed using the Azure Stack Management Portal or PowerShell.
What is the purpose of the drain operation in Azure Stack?
The drain operation in Azure Stack is used to move virtual machines and services from a node to other nodes in the cluster in preparation for maintenance or repair.
How can the repair operation be used in Azure Stack?
The repair operation in Azure Stack is used to fix hardware or software issues on a node.
What is the impact of node operations on Azure Stack Service Level Agreements (SLAs)?
Node operations in Azure Stack may impact SLAs, so it is important to plan accordingly to minimize downtime.
How can you ensure that all Azure Stack nodes and components are healthy before performing node operations?
You can use monitoring and diagnostic tools to verify the health of Azure Stack nodes and components before performing node operations.
What is the purpose of the stop operation in Azure Stack?
The stop operation in Azure Stack shuts down a node and its virtual machines and services.
How can you perform the shutdown operation in Azure Stack using PowerShell?
To perform the shutdown operation in Azure Stack using PowerShell, you can use the Stop-AzsNode cmdlet with the -ForceShutdown parameter.
What are some considerations to keep in mind when performing node operations in Azure Stack?
Considerations when performing node operations in Azure Stack include ensuring that you have a backup of your deployment, informing all relevant stakeholders and users, verifying system health, understanding the impact on SLAs, and planning for downtime.
What is the purpose of the resume operation in Azure Stack?
The resume operation in Azure Stack brings a node back online after it has been stopped.
How can you perform the start operation in Azure Stack using PowerShell?
To perform the start operation in Azure Stack using PowerShell, you can use the Start-AzsNode cmdlet.
What is the process of performing the repair operation in Azure Stack?
The repair operation in Azure Stack involves diagnosing and fixing hardware or software issues on a node.
What is the purpose of the drain operation in Azure Stack?
The drain operation in Azure Stack is used to prepare a node for maintenance or repair by moving its virtual machines and services to other nodes in the cluster.
How can you perform node operations in Azure Stack Management Portal?
You can perform node operations in Azure Stack Management Portal by navigating to the Nodes blade and selecting the node you want to manage, then clicking the corresponding operation button.
Thank you for this comprehensive overview!
Can anyone share a step-by-step process for ‘resuming’ a node?
I found this article lacking depth in the ‘repair’ operation.
Excellent guide for beginners, much appreciated!
What are the risks of frequently ‘stopping’ and ‘starting’ nodes?
How long does the ‘repair’ operation usually take?
Any tips for optimizing the ‘shutdown’ process?
When should I use ‘resume’ instead of just ‘start’?