Azure Definitions – Part 1

Azure Definitions


An Azure region is an area within geography, containing one or more datacenters networked together with low network latency. When deploying a resource (VM or storage, etc) you choose a region in which you want to deploy the resource.

Region Pair:

Each Azure region is paired with another region within the same geography, together making a regional pair, which allows replication of resources, and reducing time to recover from service interruptions like a natural disaster. Benefits of Region Pairs:

  • Physical isolation – When possible, Azure prefers at least 300 miles of separation between datacenters in a regional pair, although this isn’t practical or possible in all geographies. Physical datacenter separation reduces the likelihood of natural disasters, civil unrest, power outages, or physical network outages affecting both regions at once. Isolation is subject to the constraints within the geography (geography size, power/network infrastructure availability, regulations, etc.).
  • Platform-provided replication – Some services such as Geo-Redundant Storage provide automatic replication to the paired region.
  • Region recovery order – In the event of a broad outage, recovery of one region is prioritized out of every pair. Applications that are deployed across paired regions are guaranteed to have one of the regions recovered with priority. If an application is deployed across regions that are not paired, recovery might be delayed – in the worst case, the chosen regions may be the last two to be recovered.
  • Sequential updates – Planned Azure system updates are rolled out to paired regions sequentially (not at the same time) to minimize downtime, the effect of bugs, and logical failures in the rare event of a bad update.
  • Data residency – A region resides within the same geography as its pair (except Brazil South) to meet data residency requirements for tax and law enforcement jurisdiction purposes.

Azure doesn’t enable replication of your resources by default. You have to enable replication on the resources in your region so that they are replicated to other region in the same region pair (not in any region in other region pairs or geographies).

There is one exception to this pairing; Brazil South must be replicated to South Central US because there is only one region in Brazil or South America.

There are some special Azure regions like Azure Government, Azure Germany, Azure China, etc that are used for specific purposes only.


Azure geography is a defined area of the world that contains at least one (or more) Azure Regions. Geographies are fault-tolerant to withstand complete region failure.

In simpler terms, the Group of one or more data centers is called Region. Two or more regions are grouped as Region Pair. Note that these region pairs are only paired within a given country (when possible). Consider Geography as a continent.

Ok, Region is a group of one or more data centers. If I have to create a resource in Azure, where do I create it in a given region? Which data center? This brings availability zones.

Availability Zone:

Availability Zone is a high-availability offering that protects your applications and data from datacenter failures. Availability Zones are unique physical locations within an Azure region.  Each zone is made up of one or more data centers equipped with independent power, cooling, and networking. To ensure resiliency and high availability, there is a minimum of three separate zones in all enabled regions.

With Azure Availability Zones you can choose which Zone within that Azure Region to host a resource. This enables a more granular choice of where and how to host resources within an Azure Region.

Each Zone within an Azure Region is essentially a separate datacenter. Each Zone has an independent power source, networking, cooling, etc.

Availability Sets:


Resource Group:

Resource groups enable you to manage all your resources in an application together. Resource groups are containers that allow you to manage the resources required for your application as a single management unit.

Let’s say for the first time when you create a VM, you defined subscription, network, location, and storage account details, etc. Next time when you create a VM, you can select the resource group and all the same, subscription, location and storage account details will be applied to your second VM.

When you delete a resource group, you delete all the resources within it. Always create a resource group when you create your first VM/application.

  • resource – A manageable item that is available through Azure. Virtual machines, storage accounts, web apps, databases, and virtual networks are examples of resources.
  • resource group – A container that holds related resources for an Azure solution. The resource group includes those resources that you want to manage as a group. You decide how to allocate resources to resource groups based on what makes the most sense for your organization. See Resource groups.
  • resource provider – A service that supplies Azure resources. For example, a common resource provider is Microsoft.Compute, which supplies the virtual machine resource. Microsoft.Storage is another common resource provider. See Resource providers.
  • Resource Manager template – A JavaScript Object Notation (JSON) file that defines one or more resources to deploy to a resource group or subscription. The template can be used to deploy the resources consistently and repeatedly. See Template deployment.
  • declarative syntax – Syntax that lets you state “Here is what I intend to create” without having to write the sequence of programming commands to create it. The Resource Manager template is an example of the declarative syntax. In the file, you define the properties for the infrastructure to deploy to Azure.

Resource groups

There are some important factors to consider when defining your resource group:

  • All the resources in your group should share the same lifecycle. You deploy, update, and delete them together. If one resource, such as a database server, needs to exist on a different deployment cycle it should be in another resource group.
  • Each resource can only exist in one resource group.
  • You can add or remove a resource to a resource group at any time.
  • You can move a resource from one resource group to another group. For more information, see Move resources to new resource group or subscription.
  • A resource group can contain resources that are located in different regions.
  • A resource group can be used to scope access control for administrative actions.
  • A resource can interact with resources in other resource groups. This interaction is common when the two resources are related but don’t share the same lifecycle (for example, web apps connecting to a database).

Azure Resource Manager:

Azure Resource Manager is the deployment and management service for Azure. It provides a consistent management layer that enables you to create, update, and delete resources in your Azure subscription. You can use its access control, auditing, and tagging features to secure and organize your resources after deployment.

When you take actions through the portal, PowerShell, Azure CLI, REST APIs, or client SDKs, the Azure Resource Manager API handles your request. Because all requests are handled through the same API, you see consistent results and capabilities in all the different tools. All capabilities that are available in the portal are also available through PowerShell, Azure CLI, REST APIs, and client SDKs.

Azure VM Sets:

Azure virtual machine scale sets let you create and manage a group of identical, load-balanced VMs. The number of VM instances can automatically increase or decrease in response to demand or a defined schedule. Scale sets provide high availability to your applications and allow you to centrally manage, configure, and update a large number of VMs. With virtual machine scale sets, you can build large-scale services for areas such as compute, big data, and container workloads.

Azure Containers:

Containers are a relatively new kind of virtualization called operating system virtualization. Machine virtualization takes a single machine and simulates lots of machines (such as Hyper-V or ESXi). Containers take a single operating system installation (physical or virtual machine) and simulate lots of operating system installations.

Azure Container Instance (ACI):

Azure’s product to manage containers is called azure container instances (ACI). It is a Paas service and it is the fastest way to run a container in azure.

Azure Kubernetes Service (AKS):

The task of automating and managing a large number of containers and how they interact is known as orchestration. Kubernetes is open-source orchestration software for deploying, managing and scaling containers.

Azure Kubernetes Service (AKS) manages your hosted Kubernetes environment, making it quick and easy to deploy and manage containerized applications without container orchestration expertise. It also eliminates the burden of ongoing operations and maintenance by provisioning, upgrading, and scaling resources on-demand, without taking your applications offline.

Azure Networking:

It allows you to connect your on-premises environment to cloud securely over the internet.

Azure Virtual Network:

Azure Virtual Network (VNet) is the fundamental building block for your private network in Azure. VNet enables many types of Azure resources, such as Azure Virtual Machines (VM), to securely communicate with each other, the internet, and on-premises networks. VNet is similar to a traditional network that you’d operate in your own data center but brings with it additional benefits of Azure’s infrastructure such as scale, availability, and isolation.

Azure Load Balancer:

With Azure Load Balancer, you can scale your applications and create high availability for your services. Load Balancer supports inbound and outbound scenarios providing low latency and high throughput and scale up to millions of flows for all TCP and UDP applications.

Load Balancer distributes new inbound flows that arrive on the Load Balancer’s frontend to backend pool instances, according to rules and health probes.

Azure VPN Gateway:

Azure VPN gateways provide cross-premises connectivity between customer premises and Azure. A VPN gateway is a specific type of virtual network gateway that is used to send encrypted traffic between an Azure virtual network and an on-premises location over the public Internet. You can also use a VPN gateway to send encrypted traffic between Azure virtual networks over the Microsoft network.

Azure Application Gateway:

Azure Application Gateway is a web traffic load balancer that enables you to manage traffic to your web applications. Traditional load balancers operate at the transport layer (OSI layer 4 – TCP and UDP) and route traffic based on source IP address and port, to a destination IP address and port.

Azure Load balancer and Azure Application Gateway might look similar. Check below image from stackoverflow to know the differences.

Content Delivery Network:

A content delivery network (CDN) is a distributed network of servers that can efficiently deliver web content to users. CDNs store cached content on edge servers in point-of-presence (POP) locations that are close to end-users, to minimize latency.

Azure Storage Services:

Azure Storage is a Microsoft-managed service providing cloud storage that is highly available, secure, durable, scalable, and redundant. Azure Storage includes Azure Blobs (objects), Azure Data Lake Storage Gen2, Azure Files, Azure Queues, and Azure Tables. 

Azure Storage:

What is Block Storage

Block storage devices provide fixed-sized raw storage capacity. Each storage volume can be treated as an independent disk drive and controlled by an external server operating system. This block device can be mounted by the guest operating system as if it were a physical disk. The most common examples of Block Storage are SAN, iSCSI, and local disks.

Block storage is the most commonly used storage type for most applications. Block storage can be either locally or network-attached. Block storage devices typically are formatted with a file system like FAT32, NTFS, EXT3, and EXT4.

What is Object Storage

Block storage volumes can only be accessed when they’re attached to an operating system. But data kept on object storage devices, which consist of the object data and metadata, can be accessed directly through APIs or Http/https. You can store any kind of data, photos, videos, and log files. The object store guarantees that the data will not be lost. Object storage data can be replicated across different data centers and offer simple web services interfaces for access.

Under Azure Storage we have three storage categories:

  • Structured Data:
    It is a series of two-dimensional tables with rows and columns. Each table has its own columns, and every row in a table has the same set of columns. This model is mathematically based, and most vendors provide a dialect of the Structured Query Language (SQL) for retrieving and managing data.

    • It always follows a schema.
    • All the data have the same fields or properties.
    • It is stored in a database with rows and columns.

  • Semi-Structured Data:
    Semi-structured data is information that doesn’t reside in a relational database but that does have some organizational properties that make it easier to analyze. With some process, you can store them in relation database (it could be very hard for some kind of semi-structured data), but the semi-structure exists to ease space, clarity or compute. It is also referred to as non-relational or NoSQL data.
  • Unstructured Data:
    Unstructured data is data that is which is not organized in a pre-defined manner or does not have a pre-defined data model. There are no restrictions on the kind of data it can hold. It can hold pdf, jpg, JSON, videos and any other data types.

Azure Blob Storage:

Azure Blob storage is Microsoft’s object storage solution for the cloud. Blob storage is optimized for storing massive amounts of unstructured data. Unstructured data is data that does not adhere to a particular data model or definition, such as text or binary data.

Disk storage:

An Azure managed disk is a virtual hard disk (VHD). You can think of it as a physical disk in an on-premises server but, virtualized. Azure managed disks are stored as page blobs, which are a random IO storage object in Azure. When you select to use Azure managed disks with your workloads, Azure creates and manages the disk for you. The available types of disks are Ultra Solid State Drives (SSD) (Preview), Premium SSD, Standard SSD, and Standard Hard Disk Drives (HDD). Azure Disk storage provides disks for VMs, applications and other services.

Check this article to decide which storage to choose:

Azure File Storage:

Azure Files offers fully managed file shares in the cloud that are accessible via the industry standard Server Message Block (SMB) protocol. Azure file shares can be mounted concurrently by cloud or on-premises deployments of Windows, Linux, and macOS. Additionally, Azure file shares can be cached on Windows Servers with Azure File Sync for fast access near where the data is being used. These file shares can be mounted in any windows, Linux or Mac-OS machines.

Archive Storage:

Optimized for storing data that is rarely accessed and stored for at least 180 days with flexible latency requirements. Costs are low for storing data, but for retrieving, you will be charged again.

Different types of archiving storage given here:

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