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VM images in Azure are templates that include an operating system and preconfigured settings. To find images, you use commands like Get-AzVMImageOffer and Get-AzVMImageSku filtered by publisher and offer. These commands help you list and select the exact image you need, such as a specific Windows Server version. Picking the right image ensures your virtual machine starts with the correct software.
A VM size defines the amount of vCPUs, memory, and sometimes GPU capacity a virtual machine has. It is important to select a size that matches your workload so you do not pay for unused resources or run out of capacity. If your application needs more power, you can resize the VM later. Azure lets you change sizes to scale up or scale down as demand changes.
Azure offers several VM size categories to meet different needs. Common categories include:
To see what sizes are available in your region, use az vm list-sizes with the --location parameter. This command returns a table showing the Name, NumberOfCores, MemoryInMb, and other details for each VM size. Checking availability ensures you pick a VM size that can be provisioned where you need it.
When creating a VM, you specify the size with az vm create and the --size parameter. For example, you might choose Standard_D2s_v3 to get two cores and 8 GB of memory. To adjust resources later, use az vm resize or deallocate the VM and then resize if the new size is not available on the current cluster. Resizing triggers a VM reboot but lets you match your compute resources to changing requirements.
High availability and scalability are critical for keeping Azure virtual machines running smoothly and meeting user demands. High availability ensures that services remain online even when parts of the system fail, while scalability allows resources to grow or shrink based on workload. Azure provides built-in features to handle both needs without complex setup. Understanding these features helps you design resilient and flexible applications.
Availability sets are logical groupings of VMs that protect applications from hardware failures and maintenance events. Azure distributes the VMs in an availability set across multiple fault domains (separate racks with independent power and networking) and update domains (groups that are updated one at a time). This configuration reduces the chance of all VMs being affected simultaneously and meets a 99.95% SLA. There is no extra cost for using availability sets—only the cost of each VM instance.
Availability zones are physically separated data centers within a single Azure region. By deploying two or more VM instances across at least two zones, you achieve a 99.99% uptime SLA. Zones protect against datacenter-level failures such as power outages or cooling issues. Availability zones can be used alone or together with availability sets for even greater resilience.
Virtual Machine Scale Sets (VMSS) enable automatic scaling and group management of VMs. Scale sets let you:
VMSS provides both horizontal scaling (changing the number of VMs) and the option for manual vertical scaling (adjusting VM sizes).
Azure's scaling options help maintain performance under varying loads. For single VMs, you can manually change the size (vertical scaling), but there is no built-in way to add extra VMs (horizontal scaling). In contrast, scale sets offer auto-scaling and load balancing to handle spikes and dips automatically. By combining availability sets or zones with scale sets, you ensure both resilience and flexibility for your cloud workloads.
Azure virtual machines require several networking components to communicate and stay secure. These components include a virtual network (vNet), subnets, network interfaces (NICs), public IP addresses, and network security groups (NSGs). Each component plays a specific role in connecting VMs to each other, to the internet, and to other Azure services. Understanding these resources is essential for deploying and managing VMs in Azure.
Virtual networks are logical boundaries that isolate VM traffic within Azure. Within a vNet, subnets segment the network into smaller address ranges and act as security boundaries. You can place VMs in different subnets to control traffic flow and organize resources by application tier or function. Subnets also make it easier to apply security policies and optimize network performance.
Network interfaces (NICs) link VMs to a subnet and define how traffic enters or leaves a VM. Each NIC can be assigned a public IP address for internet connectivity. Public IP addresses can be allocated dynamically (changing when the VM deallocates) or statically (reserved across reboots). Choosing the right allocation method ensures consistent connectivity or flexibility based on your needs.
Network security groups (NSGs) serve as firewalls at the subnet or NIC level, controlling inbound and outbound traffic. NSGs contain security rules with priorities that allow or deny traffic based on ports, protocols, and IP address ranges. You can associate an NSG with a subnet to protect multiple VMs or with a NIC for more granular control. Effective NSG rule design helps secure VMs while allowing necessary communication.
When deploying a VM, these networking resources are typically created together using templates, the Azure portal, CLI, or PowerShell. A VM's network profile references its NIC, which in turn references the subnet and vNet. The NIC also ties in the public IP and NSG for connectivity and security. Coordinating these components ensures VMs are reachable, segmented, and protected in your Azure environment.
Azure virtual machines rely on disks to store the operating system and application data. Each VM automatically includes an OS disk and can have one or more data disks attached. It is a best practice to separate OS and data disks so you can protect your data if you need to redeploy or resize a VM. Understanding the different storage options helps you meet performance requirements and cost optimization goals.
The primary storage in Azure is delivered through managed disks, which are fully maintained by Azure for durability and scalability. There are three main types of managed disks:
Choosing the right disk type involves balancing cost and performance, depending on how your applications use storage.
In addition to managed disks, Azure VMs can take advantage of ephemeral disks for temporary storage. Ephemeral disks are located on the VM host, offering very low latency and high IOPS without extra charge. However, data on an ephemeral disk is lost if the VM is deallocated or moved, so it is best for cache, page files, or other non-critical data. Use ephemeral disks when you need fast local storage and can tolerate data loss during reallocation.
When planning VM storage, consider these factors to match your workload needs:
By aligning disk types with your application's needs, you ensure that your Azure VMs deliver reliable performance while keeping costs under control.
Azure Virtual Machines are on-demand, scalable compute resources that give you flexibility without owning hardware. To keep VMs running smoothly, you must perform tasks like configuring, patching, and installing software. Monitoring and management tools help automate these tasks, reduce manual work, and maintain VM health and performance. Important tools include Azure Monitor for insights, Azure Automation for runbooks, and Azure Backup for data protection.
Before creating a VM, you need to consider and deploy several supporting resources. These include:
Each resource is billed separately, so it is important to plan capacity and usage.
To estimate VM costs before deployment, use the Azure Pricing Calculator. It lets you choose options such as VM size, operating system, number of instances, and runtime hours to see a real-time cost estimate. You can also add optional resources like managed disks, storage transactions, and bandwidth to refine your budget. This planning helps you avoid unexpected charges.
After deploying VMs, monitoring costs and usage is crucial. Use Cost Management features in the Azure portal to view costs by day, month, or year. You can:
These tools help maintain financial control and ensure resources are used efficiently.
To enforce governance and further control costs, apply Azure Policy definitions. Built-in policies let you:
Custom policies can automate compliance and reduce risk, ensuring that only approved configurations are deployed.