Tutorial / Cram Notes
Azure provides a wide range of VM sizes to cater to different use cases, from general-purpose workloads to compute, memory, storage, or graphics-intensive applications. These sizes are grouped into various series, each designed for specific scenarios:
- General purpose – B, Dsv3, Dv3, Dasv4, Dav4, DSv2, Dv2, Av2
- Compute optimized – Fsv2
- Memory optimized – Esv3, Ev3, Easv4, Eav4, M, GS, G, DSv2, Dv2
- Storage optimized – Lsv2, Ls
- GPU optimized – NV, NVv3, NVv4, NC, NCv2, NCv3, ND, NDv2
- High performance compute – H, HB, HC, HBv2
When selecting a VM size, consider the core requirements of your application. A workload that demands higher processing power might benefit most from a compute optimized series, whereas applications that need to process large in-memory datasets might opt for memory optimized series.
Changing VM Sizes
There may be scenarios where you find the initial size chosen for your VM is no longer optimal. Perhaps the workload has changed or you need to adjust for better cost management. Azure makes it possible to resize a VM to suit these changing demands.
Before resizing a VM, you should:
- Confirm that the desired VM size is available in your target Azure region.
- Ensure the VM is stopped (deallocated) to avoid interruptions.
- Check your resource quotas, as moving to a larger size could require higher quotas.
To resize a VM using the Azure portal, follow these steps:
- Navigate to the desired VM in the Azure portal.
- Click on ‘Size’ in the menu under the ‘Settings’ section.
- Choose the new size from the list of available sizes.
- Click the ‘Resize’ button to apply the changes.
It’s also possible to resize a VM through Azure CLI, PowerShell, or an ARM template.
Example: Resizing a VM using Azure CLI
# Stop the VM before resizing
az vm deallocate –resource-group myResourceGroup –name myVM
# Resize the VM
az vm resize –resource-group myResourceGroup –name myVM –size Standard_DS3_v2
Monitoring and Adjusting VM Sizes
Selecting the right VM size is as much an ongoing process as it is a one-time decision. Over time, application needs could evolve, making it necessary to continually monitor your VMs’ performance to ensure they’re still the right fit.
You can monitor VM performance using Azure Monitor or third-party tools. By analyzing metrics such as CPU usage, memory pressure, and disk I/O, administrators can determine whether the VM size must be adjusted.
When determining if a VM size is adequate, look for patterns. If a VM is consistently using less than 50% of its resources, scaling down might reduce costs without impacting performance. Conversely, if a VM is frequently at or near its capacity, scaling up might help to avoid performance bottlenecks.
Considerations for VM Size Management
- Cost: Larger VM sizes cost more. Always align VM size decisions with budgetary constraints and cost optimization practices.
- Performance: Ensure the VM size provides the performance your application needs. It’s also worth considering Azure’s Premium SSD or Ultra Disk offerings for workloads that require high disk throughput and latency.
- Availability: Some VM sizes are not available in all regions, or they might be in high demand, which can influence the feasibility of resizing operations.
- VM Scale Sets: If you’re using VM scale sets, resizing operations can be applied to all VMs in the set, making it a convenient option for managing size across multiple VMs.
By thoughtfully managing VM sizes, Azure administrators can optimize the balance between cost and performance, ensuring that applications on Azure have the resources they need to run effectively while avoiding unnecessary expenses. Regularly revisiting the size of your VMs and adjusting based on current workload requirements is crucial for maintaining an efficient Azure environment.
Practice Test with Explanation
True or False: It is possible to resize a virtual machine in Azure to a larger or smaller size without deallocating it.
- False
Answer: False
Explanation: Resizing a VM generally requires you to deallocate the VM first, which means stopping the VM, before changing its size and then starting it again.
When resizing a VM in Azure, all VM sizes are compatible with every VM series.
- False
Answer: False
Explanation: Not all VM sizes are compatible with every VM series. The available sizes for a VM to resize to are constrained by the hardware and region.
Which of the following factors should be considered when choosing the size of a new VM in Azure? (Choose all that apply)
- A) Cost
- B) Workload requirements
- C) Region availability
- D) Color of the VM icon in the Azure portal
Answer: A, B, C
Explanation: When choosing a VM size, you should consider the cost, the workload requirements of the application you will be running, and whether the size is available in the region you are deploying to. The color of the icon is irrelevant.
True or False: You can change the size of an Azure VM using Azure CLI.
- True
Answer: True
Explanation: You can use Azure CLI to resize an Azure VM using the appropriate commands, provided the new size is available in the VM’s current region and hardware cluster.
The ability to move a VM to a different hardware cluster is dependent on:
- A) The VM’s operating system
- B) The compatibility of new size with the hardware cluster
- C) The color of the VM
- D) The time of day
Answer: B
Explanation: The key factor in moving a VM to a different hardware cluster when resizing is whether the chosen new size is compatible with the hardware cluster.
True or False: You need to update your VM’s configuration file manually after resizing it on the Azure portal.
- False
Answer: False
Explanation: When you resize a VM via the Azure portal, Azure automatically updates the VM’s configuration file for you.
How can you determine if a new VM size is available in your desired region? (Choose one)
- A) Check the Azure services by region page
- B) Guess based on previous experiences
- C) Consult a printed Azure regions map
- D) Based on the phase of the moon
Answer: A
Explanation: The Azure services by region page lists available services and VM sizes for each region, providing the most accurate and current information.
Before resizing a VM in Azure, you must first:
- A) Take a backup of the VM
- B) Stop any running processes inside the VM
- C) Deallocate the VM
- D) Rename the VM
Answer: C
Explanation: Before resizing a VM, you must deallocate it which stops the VM but retains the disks. Other options may be part of an administrative process but are not required by Azure.
True or False: Azure automatically adjusts the pricing to the new size as soon as the VM is resized.
- True
Answer: True
Explanation: Upon resizing your VM, Azure immediately begins charging you based on the new size’s pricing.
When dealing with VM sizes, what does ‘vCPU’ stand for?
- A) virtual Central Processing Unit
- B) very Central Processing Unit
- C) virtual Compact Performance Unit
- D) very Compact Performance Unit
Answer: A
Explanation: In Azure, vCPU stands for virtual Central Processing Unit, representing a portion of a physical CPU that is assigned to a virtual machine.
True or False: Only B-series burstable VMs allow CPU performance to vary according to workload.
- False
Answer: False
Explanation: While B-series VMs offer burstable performance, there are other VM sizes like the F-series that also allow the CPU performance to adjust based on the workload.
Which Azure feature can be used to automatically resize VMs based on their performance metrics?
- A) Azure Advisor
- B) Azure Automation
- C) Azure Autoscale
- D) Azure Monitor
Answer: C
Explanation: Azure Autoscale is a feature that enables you to automatically scale the number of VM instances up or down based on performance metrics like CPU usage or network traffic.
Interview Questions
What are virtual machine sizes in Azure?
Virtual machine sizes in Azure refer to the amount of compute, memory, and storage resources that are available to your virtual machine.
Why would I need to resize a virtual machine in Azure?
You may need to resize a virtual machine in Azure to optimize cost and performance, accommodate changes in your business operations, or meet other operational requirements.
How do I resize a virtual machine in Azure?
To resize a virtual machine in Azure, navigate to the virtual machine in the Azure portal, click on the “Size” option in the left-hand menu, select the new size for the virtual machine, review the changes, and click on the “Resize” button to apply the changes.
Can I resize a virtual machine while it is running?
No, you cannot resize a virtual machine while it is running. You must stop the virtual machine before resizing.
How long does it take to resize a virtual machine in Azure?
The time it takes to resize a virtual machine in Azure depends on various factors, such as the size of the virtual machine, the amount of data stored, and the complexity of the resizing process. Generally, the process can take anywhere from a few minutes to several hours.
What are some considerations when resizing a virtual machine in Azure?
Some considerations when resizing a virtual machine in Azure include verifying that the virtual machine is stopped before resizing, ensuring that the new size meets the resource requirements of your workload, understanding the cost implications of the new size, and verifying that the new size is available in the region where your virtual machine is located.
How do I monitor the status of a virtual machine resize in Azure?
You can monitor the status of a virtual machine resize in Azure by checking the Notifications blade in the Azure portal or by using Azure PowerShell to query the resize status.
Can I change the virtual machine size after the initial deployment?
Yes, you can change the virtual machine size after the initial deployment. This is known as resizing.
Are all virtual machine sizes available in all Azure regions?
No, not all virtual machine sizes are available in all Azure regions. You should verify that the new size is available in the region where your virtual machine is located.
Can I resize a virtual machine to a smaller size?
Yes, you can resize a virtual machine to a smaller size, but this may impact the performance and capabilities of the virtual machine.
Can I resize a virtual machine to a larger size?
Yes, you can resize a virtual machine to a larger size, but this may increase the cost and resource utilization of the virtual machine.
How do I determine the appropriate virtual machine size for my workload?
You can determine the appropriate virtual machine size for your workload by analyzing the resource requirements, performance characteristics, and cost implications of different sizes, and by testing and monitoring the performance of your workload on different sizes.
What are the benefits of resizing virtual machines in Azure?
The benefits of resizing virtual machines in Azure include optimizing cost and performance, accommodating changes in your business operations, and ensuring scalability and flexibility of your infrastructure.
Can I automate the resizing of virtual machines in Azure?
Yes, you can automate the resizing of virtual machines in Azure by using Azure Automation or other automation tools and scripts.
What should I do if there is an issue with resizing a virtual machine in Azure?
If you experience issues with resizing a virtual machine in Azure, you can review the logs, check the status of the virtual machine and its dependencies, and contact Azure support for further assistance.
This was a very informative post on managing VM sizes! Thanks!
I found that resizing VMs without downtime can be tricky. Anyone has tips on best practices?
Is it possible to resize a VM to a different series?
Great overview of the topic!
I ignored the VM sizing during initial deployment and now facing performance issues. 😔
When resizing, I noticed that my application slows down for a bit. Is this normal?
Does anyone know if there’s a cost difference when resizing a VM?
I wish they had a feature to automatically resize VMs based on usage metrics.