VM scale sets in Microsoft Azure are a powerful solution for hosting and managing identical, load-balanced Virtual Machines (VMs). By utilizing VM scale sets, administrators can manage, configure and update large numbers of VMs.
Before we dive into how to deploy and configure VM scale sets, let’s explore what they are and why we should use them.
What is a Virtual Machine Scale Set?
Azure Virtual Machine Scale Sets allow you to manage and scale up to thousands of Linux and Windows virtual machines. They provide high availability to your applications and support autoscale, allowing you to automatically adjust the number of VMs in response to the current workload or schedule.
Why use VM Scale Sets?
The primary benefit of VM Scale Sets is their ability to rapidly create and manage a large number of identical VMs. They’re designed to support true autoscaling – no pre-provisioning of VMs is required, and they include automatic load balancing across all VMs.
Deploying VM Scale Sets
Deploying VM scale sets can be done through the Azure portal, Azure PowerShell, or Azure CLI. For our example, we’ll walk through how to deploy a VM scale set through the Azure portal.
- In the Azure portal, click “Create a resource” in the top left corner.
- Search for “Virtual Machine Scale Set” and select it from the populated results.
- Click “Create”.
- Fill out the basics:
- Subscription: Select your Azure subscription.
- Resource group: Create a new one or use an existing one.
- Name: Name your scale set.
- Region: Pick the region where you want your VMs.
- Availability zone: Select the zones you want your instances in – for the highest availability, distribute them across all zones.
- Image: Choose the image for the VMs.
- Authentication type: Pick password or SSH public key.
- Under the ‘Instances’ tab:
- Initial instance count: Define the initial VM instances count.
- Size: Choose the size of your VMs.
- Click Review + create and then click Create.
Configuring VM Scale Sets
By default, the scale set uses an Azure Load Balancer for inbound access and scale sets are designed to work with Azure load balancers (either internal or internet-facing). However, there are additional settings you might want to configure.
One of the most important features to configure is the Autoscaling feature. With Autoscaling, your application can automatically scale out or scale back according to predefined rules.
To configure Autoscale:
- Within the scale set resource, click “Scaling”.
- Select “Custom Autoscale”.
- Set the minimum/maximum/default number of VMs.
- Under ‘Scale out rule’ and ‘Scale in rule’, define your conditions for scaling.
- Click ‘Save’.
For high availability, it’s recommended to use Availability Zones. Availability zone rules can be configured under the ‘Settings’ -> ‘Availability zone’ in the scale set.
By effectively deploying and configuring VM scale sets, you can ensure that your Azure virtual machines run smoothly, rapidly scale in response to demand, and provide a high level of availability. Make sure to spend time configuring your scale sets to best fit the needs of your applications and optimize your resource usage.
To successfully pass the AZ-104 Microsoft Azure Administrator exam, a solid understanding of how to deploy and manage Azure VM scale sets is crucial. With diligent study and hands-on practice, you’ll be well on your way to achieving your certification.
Practice Test
True or False: Azure VM Scale Sets allow you to manage and scale up to tens of thousands of VMs according to your application needs.
- Answer: True
Explanation: VM Scale Sets are an Azure Compute resource that you can use to deploy and manage a set of identical VMs.
True or False: You cannot increase the instance count manually in VM scale sets.
- Answer: False
Explanation: You can manually increase or decrease the instance count in VM scale sets as per your requirements.
Which of the following is used to automatically adjust the number of VM instances in response to workload changes in VM scale sets?
- A. Manual scaling
- B. Autoscaling
- C. Load balancing
- D. Bandwidth optimization
Answer: B. Autoscaling
Explanation: Autoscaling allows VM scale sets to increase or decrease the number of VM instances in response to workload changes.
True or False: VM scale sets can only use Managed Disks.
- Answer: False
Explanation: VM scale sets can use both managed and unmanaged disks.
What is the maximum number of VM instances in a single VM scale set, as of the most recent Azure update?
- A. 1000
- B. 100
- C. 50
- D. 10000
Answer: A. 1000
Explanation: You can scale up to 1000 VM instances in a single VM scale set.
True or False: VM Scale Sets are designed to support stateful applications.
- Answer: False
Explanation: VM Scale Sets are primarily designed to support stateless applications but can be modified to support stateful applications through additional configuration.
True or False: VM scale sets distribute traffic equally to all VM instances.
- Answer: True
Explanation: VM scale sets use Azure Load Balancer or Application Gateway to distribute network traffic evenly to all VM instances.
Which of the following types of load balancing solutions can be used with Azure VM scale sets?
- A. Azure Load Balancer
- B. Azure Traffic Manager
- C. Both A and B
- D. Neither A nor B
Answer: C. Both A and B
Explanation: You can use either Azure Load Balancer for layer-4 (TCP, UDP) load balancing or Azure Traffic Manager for layer-7 (HTTP, HTTPS) load balancing with VM scale sets.
What is the maximum number of fault domains that an Azure region can have?
- A. 2
- B. 3
- C. 5
- D. 10
Answer: B. 3
Explanation: The maximum number of fault domains for a single Azure region is
How many VM sizes can be specified while creating a VM Scale Set?
- A. 1
- B. 2
- C. 5
- D. There is no limit
Answer: A. 1
Explanation: While creating a VM Scale Set, only one VM size can be specified. However, this can be changed after deploying the Scale Set.
What is used by VM Scale Sets to ensure that instances run in different physical servers, compute racks, storage units, and network switches?
- A. Mesh Availability Zones
- B. Fault Domains and Update Domains
- C. Both A and B
- D. None of the above
Answer: B. Fault Domains and Update Domains
Explanation: VM Scale Sets use Fault Domains and Update Domains to ensure VM instances run in different hardware for increased resiliency.
True or False: VM Scale Sets can use Spot instances for cost optimization.
- Answer: True
Explanation: Azure allows the use of spot instances in VM Scale Sets for cost optimization by taking advantage of their low, variable pricing.
True or False: VM Scale Sets support both Windows and Linux OS platforms.
- Answer: True
Explanation: Azure VM Scale Sets support both Widows and Linux OS platforms.
What feature of VM Scale Sets provides automatic OS upgrades across all instances?
- A. Autoscale
- B. Availability Sets
- C. Automatic OS Upgrade
- D. None of the above
Answer: C. Automatic OS Upgrade
Explanation: The Automatic OS Upgrade feature of VM Scale Sets ensures that all instances run on the latest OS version by creating a rolling upgrade across instances.
True or False: VM Scale Sets can scale across multiple regions.
- Answer: False
Explanation: Azure VM Scale Sets can scale across multiple availability zones within a single region, but not across multiple regions.
Interview Questions
What does VM Scale Set in Azure mean?
Azure VM Scale sets are an Azure compute resource that you can use to deploy and manage a set of identical VMs. With all VMs configured the same, VM Scale Sets are designed to support true auto-scale, and no pre-provisioning of VMs is required.
How can you upgrade an application in Virtual Machine Scale Sets?
For upgrading an application in VM Scale Sets, you can use automated or manual upgrade. In auto mode, Azure performs the update automatically without user intervention, while in manual mode, Azure waits for the user to initiate the update process.
Can VMSS support Windows and Linux VMs?
Yes, VM scale sets support both Windows and Linux VMs.
What are the two scaling options available in VM Scale Sets?
The two scaling options available in VM Scale Sets are Manual Scale and Auto-Scale. Manual scaling specifies the instance count directly. Auto-scaling allows the user to define rules to scale out (add) or scale in (remove) instances.
How to update a VM scale set?
VM scale sets can be updated using the Azure portal, Azure CLI, Azure PowerShell, or REST API. They can also adopt a model where you provision a new scale set with the updates applied, then delete the old scale set.
Is it possible to use Azure Load Balancer and Application Gateway with VM scale sets?
Yes, VM scale sets can use Azure Load Balancer for layer 4 (TCP, UDP) load balancing, and also Application Gateway for layer 7 (HTTP, HTTPS) load balancing.
Does Azure VM scale sets require the VMs to be identically configured?
Yes, a VM scale set consists of identical VM instances which are based on the same base OS image and machine configuration.
How can you design VM scale sets for redundancy and high availability?
To design VM scale sets for redundancy and high availability, they should be combined with Availability Zones or Availability Sets.
Can VM scale sets be deployed across multiple Availability Zones in an Azure region?
Yes, VM scale sets can be deployed across multiple Availability Zones in an Azure region to protect VM scale sets from the failure of a single location.
Can custom images be used in Azure scale sets?
Yes, Azure scale sets support both platform images as well as custom images for scale set configuration.
How does Azure auto-scaling work in VM scale sets?
Auto-Scaling in VM scale sets works by enabling or disabling VM instances based on rules concerning metric data. For example, if CPU utilization of the VM instances goes beyond a certain percentage, Azure can automatically spin up new VM instances to distribute the load.
Can VM Scale Sets be integrated with Azure Service Fabric?
Yes, Azure VM Scale Sets can be integrated with Azure Service Fabric to orchestrate applications across multiple VMs.
Can VM scale sets scale across multiple storage accounts?
Yes, VM scale sets allow you to automatically distribute VM instances across multiple storage accounts.
What is the maximum number of VMs in a Scale Set?
The maximum limit of VMs in a scale set is 1000 when using Azure platform images, while it’s 600 when using custom images.
How can I increase the limit of VM instances in a scale set?
To increase the limit of VM instances in a Scale Set, you can use application partitioning, splitting the scale set into smaller units. However, you must manage the orchestration across scale sets by yourself.
extutorials.com