Category Archives: Azure Stack HCI

Maximize the performance of Azure Stack HCI: discover the best configurations for networking

Hyperconverged infrastructure (HCI) are increasingly popular as they allow you to simplify the management of the IT environment, reduce costs and scale easily when needed. Azure Stack HCI is the Microsoft solution that allows you to create a hyper-converged infrastructure for the execution of workloads in an on-premises environment and which provides a strategic connection to various Azure services to modernize your IT infrastructure. Properly configuring Azure Stack HCI networking is critical to ensuring security, application reliability and performance. In this article, the fundamentals of configuring Azure Stack HCI networking are explored, learning more about available networking options and best practices for networking design and configuration.

There are different network models that you can take as a reference to design, deploy and configure Azure Stack HCI. The following paragraphs show the main aspects to consider in order to direct the possible implementation choices at the network level.

Number of nodes that make up the Azure Stack HCI cluster

A single Azure Stack HCI cluster can consist of a single node and can scale up to 16 nodes.

If the cluster consists of a single server at the physical level it is recommended to provide the following network components, also shown in the image:

single TOR switch (L2 or L3) for north-south traffic;
two-four teamed network ports to handle management and computational traffic connected to the switch;

Furthermore, optionally it is possible to provide the following components:

two RDMA NIC, useful if you plan to add a second server to the cluster to scale your setup;
a BMC card for remote management of the environment.

Figure 1 – Network architecture for an Azure Stack HCI cluster consisting of a single server

If your Azure Stack HCI cluster consists of two or more nodes you need to investigate the following parameters.

Need for Top-Of-Rack switches (TOR) and its level of redundancy

For Azure Stack HCI clusters consisting of two or more nodes, in production environment, the presence of two TOR switches is strongly recommended, so that we can tolerate communication disruptions regarding north-south traffic, in case of failure or maintenance of the single physical switch.

If the Azure Stack HCI cluster is made up of two nodes, you can avoid providing a switch connectivity for storage traffic.

Two-node configuration without TOR switch for storage communication

In an Azure Stack HCI cluster that consists of only two nodes, to reduce switch costs, perhaps going to use switches already in possession, storage RDMA NICs can be connected in full-mesh mode.

In certain scenarios, which include for example branch office, or laboratories, the following network model can be adopted which provides for a single TOR switch. By applying this pattern, you get cluster-wide fault tolerance, and is suitable if interruptions in north-south connectivity can be tolerated when the single physical switch fails or requires maintenance.

Figure 2 – Network architecture for an Azure Stack HCI cluster consisting of two servers, without storage switches and with a single TOR switch

Although the SDN services L3 are fully supported for this scheme, routing services such as BGP will need to be configured on the firewall device that sits on top of the TOR switch, if this does not support L3 services.

If you want to obtain greater fault tolerance for all network components, the following architecture can be provided, which provides two redundant TOR switches:

Figure 3 – Network architecture for an Azure Stack HCI cluster consisting of two servers, without storage switches and redundant TOR switches

The SDN services L3 are fully supported by this scheme. Routing services such as BGP can be configured directly on TOR switches if they support L3 services. Features related to network security do not require additional configuration for the firewall device, since they are implemented at the virtual network adapter level.

At the physical level, it is recommended to provide the following network components for each server:

two-four teamed network ports, to handle management and computational traffic, connected to the TOR switches;
two RDMA NICs in a full-mesh configuration for east-west traffic for storage. Each cluster node must have a redundant connection to the other cluster node;
as optional, a BMC card for remote management of the environment.

In both cases the following connectivities are required:

Networks	Management and computational	Storage	BMC
Network speed	At least 1 GBps, 10 GBps recommended	At least 10 GBps	Tbd
Type of interface	RJ45, SFP+ or SFP28	SFP+ or SFP28	RJ45
Ports and aggregation	Twofour ports in teaming	Two standalone ports	One port

Two or more node configuration using TOR switches also for storage communication

When you expect an Azure Stack HCI cluster composed of more than two nodes or if you don't want to preclude the possibility of being able to easily add more nodes to the cluster, it is also necessary to merge the traffic concerning the storage from the TOR switches. In these scenarios, a configuration can be envisaged where dedicated network cards are maintained for storage traffic (non-converged), as shown in the following picture:

Figure 4 – Network architecture for an Azure Stack HCI cluster consisting of two or more servers, redundant TOR switches also used for storage traffic and non-converged configuration

At the physical level, it is recommended to provide the following network components for each server:

two teamed NICs to handle management and computational traffic. Each NIC is connected to a different TOR switch;
two RDMA NICs in standalone configuration. Each NIC is connected to a different TOR switch. SMB multi-channel functionality ensures path aggregation and fault tolerance;
as optional, a BMC card for remote management of the environment.

These are the connections provided:

Networks	Management and computational	Storage	BMC
Network speed	At least 1 GBps, 10 GBps recommended	At least 10 GBps	Tbd
Type of interface	RJ45, SFP+ or SFP28	SFP+ or SFP28	RJ45
Ports and aggregation	Two ports in teaming	Two standalone ports	One port

Another possibility to consider is a "fully-converged" configuration of the network cards, as shown in the following image:

Figure 5 – Network architecture for an Azure Stack HCI cluster consisting of two or more servers, redundant TOR switches also used for storage traffic and fully-converged configuration

The latter solution is preferable when:

bandwidth requirements for north-south traffic do not require dedicated cards;
the physical ports of the switches are a small number;
you want to keep the costs of the solution low.

At the physical level, it is recommended to provide the following network components for each server:

two teamed RDMA NICs for traffic management, computational and storage. Each NIC is connected to a different TOR switch. SMB multi-channel functionality ensures path aggregation and fault tolerance;
as optional, a BMC card for remote management of the environment.

These are the connections provided:

Networks	Management, computational and storage	BMC
Network speed	At least 10 GBps	Tbd
Type of interface	SFP+ or SFP28	RJ45
Ports and aggregation	Two ports in teaming	One port

SDN L3 services are fully supported by both of the above models. Routing services such as BGP can be configured directly on TOR switches if they support L3 services. Features related to network security do not require additional configuration for the firewall device, since they are implemented at the virtual network adapter level.

Type of traffic that must pass through the TOR switches

To choose the most suitable TOR switches it is necessary to evaluate the network traffic that will flow from these network devices, which can be divided into:

management traffic;
computational traffic (generated by the workloads hosted by the cluster), which can be divided into two categories:
- standard traffic;
- SDN traffic;
storage traffic.

Microsoft has recently changed its approach to this. In fact,, TOR switches are no longer required to meet every network requirement regarding various features, regardless of the type of traffic for which the switch is used. This allows you to have physical switches supported according to the type of traffic they carry and allows you to choose from a greater number of network devices at a lower cost, but always of quality.

In this document lists the required industry standards for specific network switch roles used in Azure Stack HCI implementations. These standards help ensure reliable communication between nodes in Azure Stack HCI clusters. In this section instead, the switch models supported by the various vendors are shown, based on the type of traffic expected.

Conclusions

Properly configuring Azure Stack HCI networking is critical to ensuring that hyper-converged infrastructure runs smoothly, ensuring security, optimum performance and reliability. This article covered the basics of configuring Azure Stack HCI networking, analyzing the available network options. The advice is to always carefully plan the networking aspects of Azure Stack HCI, choosing the most appropriate network option for your business needs and following implementation best practices.

The cost model for Azure Stack HCI (12/2022)

Technologies from different vendors are available on the market that allow you to build hyper-converged infrastructures (HCI). Microsoft in this sector offers an innovative solution called Azure Stack HCI, deployed as an Azure service, that allows you to achieve high performance, with advanced security features and native integration with various Azure services. This article describes how much you need to invest to get the Azure Stack HCI solution and what aspects you can consider to structure the cost model as you like..

Premise: OPEX vs CAPEX

The term CAPEX (contraction from CAPital EXpenditure, ie capital expenditures) indicates the cost of developing or providing durable assets for a product or system.

Its counterpart, operational expenditure or OPEX (from the English term OPerational EXpenditure) is the cost of managing a product, a solution or a system. These are also called costs O&M (Operation and Maintenance) or operating and management costs.

CAPEX costs usually require a budget and a spending plan. Also for these reasons, companies generally prefer to incur OPEX costs, as they are easier to plan and manage.

Clarify these concepts, now let's see the Azure Stack HCI cost model and how to get a totally OPEX model.

Hardware costs

In order to activate the Azure Stack HCI solution, it is necessary to have on-premise hardware to run the dedicated operating system of the solution and to run the various workloads. There are two possibilities:

Azure Stack HCI Integrated Systems: determined by the vendor, offer specially structured and integrated systems for this solution, that provide an appliance-like experience. These solutions also include integrated support, jointly between the vendor and Microsoft.
Azure Stack HCI validated nodes: implementation takes place using hardware specifically tested and validated by a vendor. In this way you can customize the hardware solution according to your needs, going to configure the processor, memory, storage and features of network adapters, but respecting the supplier's compatibility matrices. There are several hardware vendors that offer suitable solutions to runAzure Stack HCI and can be consulted by accessingthis link. Most implementations are done in this way.

Figure 1 - Hardware deployment scenarios

Also for the hardware it is possible to make some evaluations to adopt a cost model based on rental. In fact,, major vendors such as HPE, Dell and Lenovo, are able to offer the necessary hardware in "infrastructure as-a-service" mode, through a payment model based on use.

Azure costs

Despite being running on premise, Azure Stack HCI provides for billing based on Azure subscription, just like any other service in Microsoft's public cloud.

Azure Stack HCI offers a free trial period that allows you to evaluate the solution in detail. The duration of this period is equal to 60 days and starts from when you complete the registration of the cluster environment in Azure.

At the end of the trial period, the model is simple and costs “10 € / physical core / month"*. The cost is therefore given by the total of physical cores present in the processors of the Azure Stack HCI cluster. This model does not provide for a minimum or a maximum on the number of physical cores licensed, much less limits on the activation duration.

Financial benefits for customers with a Software Assurance agreement

Customers who have Windows Server Datacenter licenses with active Software Assurance, can activate’Azure Hybrid Benefit also for Azure Stack HCI cluster. To activate this benefit, at no additional cost, you will need to exchange a Windows Server Datacenter core license with Software Assurance for an Azure Stack HCI physical core. This aspect allows to zero the Azure costs for the Azure Stack HCI host fee and provides the right to run an unlimited number of Windows Server guest virtual machines on the Azure Stack HCI cluster.

Furthermore, Azure Hybrid Benefits can also be activated for Azure Kubernetes Service (AKS). In this case, Windows Server StandardDatacenter licenses with active Software Assurance are required, or the presence of a Cloud Solution Provider subscription (CSP). Each Windows Server core license entitles you to use an AKS virtual core.

In the following image it is summarized as, customers with Software Assurance, can use Azure Hybrid Benefit to further reduce costs in the cloud, in on-premises datacenters and peripheral offices.

Figure 2 – What is included in the Azure Hybrid Benefit for customers in Software Assurance

Specifically for customers with a Software Assurance agreement, the adoption of Azure Stack HCI translates into a drastic reduction in the costs of modernizing the virtualization environment, making this solution even more competitive from a cost point of view compared to competitors on the market. To consult in detail the licensing requirements you can refer to this document.

Costs for guest VMs

The Azure costs listed in the previous paragraph do not include the operating system costs for guest machines running in the Azure Stack HCI environment. This aspect is also common to other HCI platforms, like Nutanix and VMware vSAN.

The following image shows how the licensing of guest operating systems can take place:

Figure 3 – Licensing of guest operating systems

Costs for Windows Server virtual machines

There are mainly two options for licensing Windows Server guest machines in Azure Stack HCI:

Buy Windows Server licenses (CAPEX mode), Standard or Datacenter, which include the right to activate the OS of guest virtual machines. The Standard Edition may be suitable if the number of Windows Server guest machines is limited, while if there are several Windows Server guest systems, it is advisable to evaluate the Datacenter Edition which gives the right to activate an unlimited number of virtualized Windows Server systems.
Pay for the Windows Server license for guest systems through your Azure subscription, just like in Azure environment. Choosing this option will incur a cost (OPEX) bet a “€22.4 / physical core / month ”* to be able to activate an unlimited number of Windows Server guest systems in the Azure Stack HCI environment.

*Costs estimated for the West Europe region and subject to change. For more details on the costs of Azure Stack HCI you can consult the Microsoft's official page.

Charges for other workloads running on Azure Stack HCI

The result we intend to pursue with the Azure Stack HCI infrastructure is to be able to run in an on-premises environment, not just virtual machines, but the same Microsoft public cloud workloads. To achieve this Microsoft is bringing the most popular Azure workloads to Azure Stack HCI and the following cost considerations apply to each of them:

Azure Kubernetes Service: the configuration of the K8s Arc enabled cluster is free **.
Azure Arc-enabled data services:
- For SQL Server, customers can purchase SQL Server licenses in CAPEX mode or, who already has SQL licenses, can use Azure Hybrid Benefit for Azure Arc-enabled SQL Managed Instance, without having to pay the SQL license again.
- If you want to switch to an OPEX model, you can obtain Microsoft SQL Server licenses through Microsoft's Azure Arc-enabled data services **.
Azure Virtual Desktop:
- User access rights for Azure Virtual Desktop. The same licenses that grant access to Azure virtual desktops in the cloud also apply to Azure Virtual Desktop in Azure Stack HCI.
- Azure Virtual Desktop Hybrid Service Fee. This fee is charged for each virtual CPU (vCPU) used by Azure Virtual Desktop session hosts running in Azure Stack HCI environment.

**For more details on Azure Arc costs you can consult this page.

Support costs

Azure Stack HCI, being in effect an Azure solution, is covered by Azure support with the following features:

A choice is provided between several Azure support plans, depending on your needs. Basic support is free, but in certain scenarios it is recommended that you at least consider Standard support, which provides a fixed monthly cost.
Technical support is provided by a team of experts dedicated to supporting the Azure Stack HCI solution and can be easily requested directly from the Azure portal.

Conclusions

Azure Stack HCI allows you to bring cloud innovation into your data center and at the same time create a strategic link to Azure. In the era of hybrid datacenters, a solution like Azure Stack HCI, allows you to structure the cost model at will and to have maximum flexibility. There are several vendors on the market offering solutions to build hyper-converged infrastructures (HCI) hybrid, and Azure Stack HCI can be very competitive, not only from the point of view of functionality, but also from the point of view of costs.

4 good reasons to choose Azure Stack HCI

Cloud computing is increasingly popular for companies looking to simplify management and achieve greater scalability of their IT environment. However, many organizations continue to use infrastructure at their datacenters for a variety of reasons, ranging from the need to ensure support for legacy workloads, the need to comply with specific technical and regulatory requirements. This article discusses the top reasons why you should consider adopting Azure Stack HCI over other on-premises virtualization solutions.

Azure Stack HCI is the Microsoft solution that allows you to create a hyper-converged infrastructure (HCI) for running workloads in an on-premises environment and that provides a strategic connection to various Azure services. Azure Stack HCI was specifically designed by Microsoft to help customers modernize their hybrid datacenter, offering a complete and familiar Azure experience in an on-premises environment. If there is an insight into the Microsoft Azure Stack HCI solution, I invite you to read this article or to view this video.

Figure 1 – Overview of Azure Stack HCI

Interacting with customers on a daily basis, I am often asked why they should choose Azure Stack HCI over other known solutions that have been on the market for a long time. In the following paragraphs I report those that, in my view, are the main reasons that lead to the adoption of Azure Stack HCI.

1. Modernize your on-premises infrastructure by bringing innovation

Azure Stack HCI is not synonymous with a virtualization environment, but it allows you to achieve much more. In fact,, it is ideal if you want to modernize your infrastructure, adopting a hyper-converged architecture that allows you to:

Activate virtual machines relying on consolidated technologies that make the environment stable and highly available, also particularly suitable for workloads that require high performance and high scalability.
Deploy and manage modern applications based on micro-services, parallel to virtual machines, on the same cluster environment, adopting Azure Kubernetes Service (AKS). As well as being able to run containerized Windows and Linux apps, AKS provides the infrastructure to run services PaaS selected of the Azure platform in an on-premises environment, thanks to Azure Arc.
Activate virtual machines with Windows Server 2022 Azure Datacenter edition, which offers specific features not available in the classic Standard and Datacenter editions. To learn more about the features available in this edition, you can consult this article.
Create session host pools of Azure Virtual Desktop using virtual machines running on-premises. This hybrid scenario becomes interesting in situations where applications are sensitive to latency, such as video editing, or scenarios where users need to take advantage of a legacy system present on-premises that cannot be easily reached.
Extend the functionality of the on-premises solution by connecting to various Azure services such as Azure Site Recovery, Azure Backup, Azure Monitor and Defender for Cloud. This aspect guarantees a constant innovation, given the continuous evolution of cloud services.

2. Optimize costs

The cost model for Azure Stack HCI, described in detail in this article, is very simple.

In particular, for customers with a Software Assurance contract, the adoption of Azure Stack HCI translates into a drastic reduction in the costs of modernizing the virtualization environment, making this solution even more competitive from a cost point of view compared to competitors on the market. Recently, doing a cost comparison between Azure Stack HCI and VMware vSphere + vSAN on a projection of 3 years, it emerged as Azure Stack HCI allows you to save up to 40%.

3. Increase the level of security

Azure Stack HCI offers cross-security across hardware and firmware, integrated into the functionalities of the operating system, that can help protect servers from advanced threats. In fact,, Azure Stack HCI systems, can adopt the security features of Secured-core, all through an easy setup experience from the Windows Admin Center.

Furthermore, Azure Stack HCI allows you to get free, just like in Azure, important security patches for Microsoft's legacy products that are past their end of support, through the Extended Security Update program (ESU). Currently applies to Windows Server 2008/R2 and will soon also apply to Windows Server 2012/R2 when end of support is reached, in addition to the corresponding versions of SQL Server. This allows you to have more time to undertake an application modernization process, without neglecting the safety aspects.

4. Maximize the investments already made

Azure Stack HCI can integrate with your existing environment as well as popular third-party solutions. Therefore, the adoption of this solution does not require new investments to introduce or adapt the management solutions, identity, security and protection.

In particular, the administrative management of Azure Stack HCI does not require specific software, but you can use existing management tools such as Admin Center, PowerShell, System Center Virtual Machine Manager and even third-party tools. Furthermore, by adopting Azure Stack HCI and Azure Arc it is possible to apply the cloud management models also to the on-premises environment, greatly simplifying the user experience.

Azure Stack HCI allows you to take full advantage of not only the investments already made in terms of tools, but also with regard to the skills of the IT staff.

Conclusions

Microsoft brings cloud innovation and experience managing one of the world's largest data centers to Azure Stack HCI. Customers, in turn, by adopting Azure Stack HCI they can modernize their on-premises datacenter, safeguarding the investments made and future ones, without neglecting the aspects related to security and integration. The reasons described in this article are particularly important, to the point of having already led several customers to choose Azure Stack HCI over other solutions in this area.

Azure Stack HCI: the constantly evolving hyper-converged solution – edition of November 2022

Azure Stack HCI is the solution that allows you to create a hyper-converged infrastructure (HCI) for running workloads in an on-premises environment and that provides a strategic connection to various Azure services. Azure Stack HCI is also considered as a hybrid service of Azure and as such it is constantly evolving. Microsoft recently introduced a series of new features that pave the way for new Azure Stack HCI adoption scenarios and allow you to better manage your hybrid infrastructure based on this solution.. This article reports the main aspects that have undergone an evolution and the new features recently introduced in Azure Stack HCI.

Financial benefits for customers with a Software Assurance agreement

In the following image it is summarized as, customers with Software Assurance, can use Azure Hybrid Benefit to further reduce costs in the cloud, in on-premises datacenters and peripheral offices.

Figure 1 – What is included in the Azure Hybrid Benefit for customers in Software Assurance

22H2 update

The new update, known as “version 22H2” or “22H2 feature update”, has been officially released and is ready for use in the production environment. This version brings higher quality on several fronts of the solution.

The following points summarize the various features and the various improvements introduced to the Azure Stack HCI operating system, version 22H2:

Network ATC v2 is able to automatically assign IP addresses to intra-cluster storage networks and automatically name cluster networks based on their intended use. It can also manage the live migration settings, such as network selection, transport and bandwidth allocation.
Storage management is more flexible as existing storage volumes can be modified to increase their resilience (for example, passing from a two-way to a three-way mirror) or perform an in-place conversion from fixed provisioning to a thin one.
Storage replication in a stretched cluster is faster with the new optional compression capability.
Hyper-V live migration is more reliable for clusters to 2 and 3 nodes without the presence of specific switches.
On the networking side, a new tag-based network segmentation option is also available, which helps protect virtualized workloads from threats based on custom tags that are assigned.

To consult all the details relating to the 22H2 version you can consult this document.

All existing Azure Stack HCI clusters can receive the 22H2 update as a free over-the-air update and you can apply the update without interruption thanks to the cluster-aware update. Microsoft recommends version 22H2 for all new Azure Stack HCI implementations.

The management tools have also been revamped to support the functionality of this new update. In fact,, you can use Windows Admin Center to manage version 22H2. Furthermore, compatibility with System Center Virtual Machine Manager and Operations Manager is maintained, thanks to the first Update Rollup (UR1) for System Center 2022, which will add official support for Azure Stack HCI, version 22H2.

Azure Arc-enabled VM management

By adopting Azure Stack HCI and Azure Arc, cloud management models can also be applied to the on-premises environment. Earlier this year, Microsoft released the public preview for managing Azure Arc-enabled virtual machines, which allows you to deploy virtual machines on Azure Stack HCI via ARM, Azure CLI and Azure portal.

In this context, important new features have been introduced:

In addition to the use of customized images, images can now be accessed directly from the Azure Marketplace. This allows you to quickly deploy the latest fully updated Microsoft images, including Windows Server 2022 Azure Edition with hotpatching and Windows 11 Enterprise multi-session for Azure Virtual Desktop. Third party images will also be available in the future. This feature is natively integrated into Azure Arc and is designed to respect network bandwidth. In fact,, the images are optimized to minimize file size and you only need to download them once to create even several virtual machines.
When deploying a new VM in Azure Stack HCI through Azure Arc, the guest operating system is now automatically Arc-enabled. This means it is possible to use extensions for VMs, as Domain Join or Custom Script to deploy and configure applications. Other extensions will also be available in the future.

Azure Hybrid Kubernetes Service

Many enterprises have a mix of deprecated virtualization applications and new container-based applications. By adopting Azure Kubernetes Service (AKS) in the Azure Stack HCI environment it is possible to distribute and manage containerized applications in parallel with virtual machines, on the same physical server or cluster environment.

The update of September 2022 for AKS on Azure Stack HCI has introduced some significant improvements, including:

The Linux container base image has been updated to Mariner 2.0, which is smaller in size and safer.
The integration of software-defined networking (SDN) is available and ready for use in the production environment.
The procedure for connecting GPUs to containers has been simplified.
Introduces the ability to use any account in the system Administrators group to manage AKS.

The ability to provision hybrid AKS clusters directly from Azure was also recently introduced, using an AAD identity. The distribution of new Kubernetes clusters in the on-premises environment is done through the Arc Resource Bridge, very similar to managing Arc-enabled virtual machines. This is an important evolution towards a simple and consistent end-to-end application provisioning experience, that embraces the cloud and the edge.

Hardware designed, shipped and supported directly by Microsoft

Microsoft announced that in the 2023 will offer a hardware-based Azure Stack HCI system designed, shipped and supported directly from the house in Redmond.

The solution, called “Pro 2”, has the following features:

Compact form factor of only 2U at half depth, also ideal for deployments outside the data center (ex. retail, manufacturing and healthcare environments).
Tamper resistant.
Quiet enough for an office environment, generating less than 60 dBA of acoustic noise.
Orderable directly from the Azure portal and supplied with pre-installed Azure Stack HCI.
Available in different configurations, with specifications suitable for different use cases.
Hardware management fully integrated with existing cluster management tools, including a new Windows Admin Center extension under development.

This upcoming release enables customers to adopt a consistent business model between the cloud and the edge: an OPEX payment model with the possibility of using Azure commitments to obtain a complete Microsoft solution, including hardware.

Conclusions

Thanks to constant improvement, the continuous introduction of new features and the inclusion of new usage scenarios, Microsoft's proposition for hyper-converged scenarios is increasingly complete, integrated and performing. Azure Stack HCI integrates perfectly with the existing on-premises environment and offers an important added value: the ability to connect Azure Stack HCI with other Azure services to obtain a hybrid hyper-converged solution. This aspect in particular strongly differentiates it from other competitors who offer solutions in this area.

The cost model for Azure Stack HCI

Technologies from different vendors are available on the market that allow you to build hyper-converged infrastructures (HCI). Microsoft in this sector offers an innovative solution called Azure Stack HCI, deployed as an Azure service, that allows you to achieve high performance, the latest security features and native integration with Azure services. This article describes how much you need to invest to get the Azure Stack HCI solution and what aspects you can consider to structure the cost model as you like..

Premise: OPEX vs CAPEX

The term CAPEX (contraction from CAPital EXpenditure, ie capital expenditures) indicates the cost of developing or providing durable assets for a product or system.

CAPEX costs usually require a budget and a spending plan. Also for these reasons, companies generally prefer to incur OPEX costs, as they are easier to plan and manage.

Clarify these concepts, now let's see the Azure Stack HCI cost model and how to get a totally OPEX model.

Hardware costs

Azure Stack HCI Integrated Systems: determined by the vendor, offer specially structured and integrated systems for this solution, that provide an appliance-like experience. These solutions also include integrated support, jointly between the vendor and Microsoft.
Azure Stack HCI validated nodes: implementation takes place using hardware specifically tested and validated by a vendor. In this way you can customize the hardware solution according to your needs, going to configure the processor, memory, storage and features of network adapters, but respecting the supplier's compatibility matrices. There are several hardware vendors that offer suitable solutions to run Azure Stack HCIand can be consulted by accessing this link. Most implementations are done in this way.

Figure 1 - Hardware deployment scenarios

Azure costs

Despite being running on premise, Azure Stack HCI provides for billing based on Azure subscription, just like any other service in Microsoft's public cloud.

Costs for Windows Server machines

Buy Windows Server licenses (CAPEX mode), Standard or Datacenter, which include the right to activate the OS of guest virtual machines. The Standard Edition may be suitable if the number of Windows Server guest machines is limited, while if there are several Windows Server guest systems, it is advisable to evaluate the Datacenter Edition which gives the right to activate an unlimited number of virtualized Windows Server systems.
Pay for the Windows Server license for guest systems through your Azure subscription, just like in Azure environment. Choosing this option will incur a cost (OPEX) equal to "22.2 € / physical core / month ”* to be able to activate an unlimited number of Windows Server guest systems in the Azure Stack HCI environment.

*Costs estimated for the West Europe region and subject to change. For more details on the costs of Azure Stack HCI you can consult the Microsoft's official page.

Charges for other workloads running on Azure Stack HCI

Azure Kubernetes Service: the configuration of the K8s Arc enabled cluster is free **.
Azure Arc-enabled data services:
- For SQL Server, customers can purchase SQL Server licenses in CAPEX mode or, who already has SQL licenses, can use Azure Hybrid Benefit for Azure Arc-enabled SQL Managed Instance, without having to pay the SQL license again.
- If you want to switch to an OPEX model, you can obtain Microsoft SQL Server licenses through Microsoft's Azure Arc-enabled data services **.
Azure Virtual Desktop:
- User access rights for Azure Virtual Desktop. The same licenses that grant access to Azure virtual desktops in the cloud also apply to Azure Virtual Desktop in Azure Stack HCI.
- Azure Virtual Desktop Hybrid Service Fee. This fee is charged for each virtual CPU (vCPU) used by Azure Virtual Desktop session hosts running in Azure Stack HCI environment.

**For more details on Azure Arc costs you can consult this page.

Support costs

Azure Stack HCI, being in effect an Azure solution, is covered by Azure support with the following features:

A choice is provided between several Azure support plans, depending on your needs. Basic support is free, but in certain scenarios it is recommended that you at least consider Standard support, which provides a fixed monthly cost.
Support is provided by a team of experts dedicated to supporting the Azure Stack HCI solution.
You can easily request technical support directly from the Azure portal.

Conclusions

Azure Stack HCI allows you to bring cloud innovation into your datacenter and at the same time create a bridge to Azure. In the era of hybrid datacenters, a solution like Azure Stack HCI, allows you to structure the cost model as you wish and to have maximum flexibility. There are several vendors on the market offering solutions to build hyper-converged infrastructures (HCI) hybrid, and Azure Stack HCI can be very competitive, not only from the point of view of functionality, but also from the point of view of costs.

How to modernize your infrastructure and get the benefits of Azure with a single on-premises server

Azure Stack HCI is the Microsoft solution that allows you to create a hyper-converged infrastructure (HCI) for running workloads in an on-premises environment and that provides a strategic connection to various Azure services. Microsoft recently introduced the ability to create an Azure Stack HCI cluster consisting of a single server. This possibility opens up new scenarios regarding the adoption of this solution. This article reports the main use cases, the aspects to consider and the benefits that can be obtained by activating Azure Stack HCI on a single server system.

In a hyper-converged infrastructure (HCI), several hardware components are removed, substitutes from the software, able to combine the layer of compute, storage and network in one solution. In this way there is a transition from a traditional "three tier" infrastructure, composed of network switches, appliance, physical systems with onboard hypervisors, storage fabric and SAN, toward hyper-converged infrastructure (HCI).

Figure 1 – "Three Tier" Infrastructure vs Hyper-Converged Infrastructure (HCI)

Azure Stack HCI is a stack made up of hardware and software that customers also use for the potential of simple integration with the Microsoft Azure cloud.

Use cases of Azure Stack HCI consisting of multiple nodes

The use of a standard Azure Stack HCI configuration consisting of multiple nodes is suitable if:

You want to modernize your infrastructure, adopting a simple hyper-converged architecture based on established technologies. Ideal for both existing workloads in the main datacenter and for branch office scenarios that require high resilience.
You want to provide for an extension of the functionality of the on-premises solution, which guarantees resilience, connecting to Azure. This aspect guarantees a constant innovation, the evolution of cloud services and the possibility to take advantage of a common set of tools, simplifying the user experience.
You want a suitable solution to host workloads that require high performance and high scalability.
It is considered useful to innovate your datacenter, as you have the ability to activate AKS clusters and deploy cloud native apps and Azure Arc-enabled services in high availability. All this thanks to the tight integration of AKS in the Azure Stack HCI environment.

Figure 2 - Use cases of Azure Stack HCI with multiple nodes

Use cases of Azure Stack HCI with a single node

Thanks to the possibility of activating an Azure Stack HCI cluster even with a single server, it is possible to contemplate new usage scenarios, including:

Activation of Azure Stack HCI in environments where there are no particular needs in terms of resilience, such as branch offices.
Adoption of a solution in environments where the ability to scale easily is required, starting initially from a single node to potentially go up to 16 nodes, if necessary.
Need to activate a solution with a small footprint, perhaps in locations with physical space constraints and at the same time allowing to keep hardware costs and operating costs low.
Ability to create and maintain test and development environments more easily.

Comparison between single node and multi-node Azure Stack HCI clusters

From the point of view of functionality, Azure Stack HCI clusters made up of a single node offer a feature set that is very similar to traditional clusters made up of multiple nodes, like:

Native integration with Azure Arc, key element for innovation and modernization of the infrastructure.
Ability to add servers horizontally to increase the scalability of the cluster environment.
Integration with Azure services.
Support for the same workloads, like Azure Virtual Desktop (AVD) and Azure Kubernetes Service (AKS).

For a complete comparison of the features you can consult this Microsoft's document.

Single node Azure Stack HCI clusters currently have the following limitations:

Installation must be done using PowerShell commands and configuration support is not yet available through the Windows Admin Center.
They are resilient to some errors, for example the presence of a failed disk, but the limited capabilities in terms of resilience dictate that they must be composed of only one type of disk drive, NVMe or SSD (not combinable with each other). This implies that there is no possibility of having cache levels.
Not all hardware vendors currently have supported solutions. To check availability, you can consult the Microsoft catalog of Azure Stack HCI solutions.

Conclusions

The possibility of activating an Azure Stack HCI cluster with only one physical server introduces greater flexibility and greatly expands the possibilities of adopting this solution. Furthermore, this choice denotes how Azure Stack HCI is the future of virtualization and software-defined solutions at Microsoft. By adopting Azure Stack HCI it is possible to bring innovation even within your datacenter thanks to a solution that is constantly updated and able to easily integrate with Azure services.

Datacenter Modernization: a real case with Microsoft solutions

The statistics speak for themselves, beyond the 90% some companies already have or foresee, in the short term, to adopt a hybrid strategy for their IT infrastructure. These data are confirmed by the daily events, where several customers include in their investment plans both the maintenance of workloads on on-premises infrastructures, both the adoption of solutions in the public cloud. At the same time, a process of modernization of applications is supported with the aim of making the most of the potential and innovation offered by these infrastructures. So we live in the era of hybrid cloud and Microsoft offers several interesting solutions to modernize datacenter and easily manage hybrid infrastructure. This article gives a real example of how a customer has embarked on the modernization path of their datacenter thanks to Azure Stack HCI and how, via Azure Arc, was able to extend Azure services and management principles to its on-premises infrastructure as well.

Initial customer request and problems to be solved

The customer in question wanted to activate a new modern and integrated virtualization infrastructure at their datacenter, to allow you to configure quickly, dynamic and flexible application workloads. The infrastructure in use by the customer was not adequate and encountered various problems, including:

Non-scalable and inflexible virtualization solution
Hardware obsolescence
Configurations that did not ensure adequate availability of virtualized systems
Performance and stability issues
Difficulty in managing the various infrastructure components

Characteristics of the proposed solutions, adopted and benefits obtained

The customer has decided to adopt a hyper-converged infrastructure (HCI), where several hardware components have been removed, replaced by software that can merge layers of compute, storage and network in one solution. In this way it made a transition from a traditional "three tier" infrastructure, composed of network switches, appliance, physical systems with onboard hypervisors, storage fabric and SAN, toward hyper-converged infrastructure (HCI).

Figure 1 - Transition from a "Three Tier" infrastructure to a Hyper-Converged Infrastructure (HCI)

Azure Stack HCI: the complete stack of the Hyper-Converged infrastructure

This was all done by adopting the solution Microsoft Azure Stack HCI, which allows the execution of workloads and an easy connection to Azure of the hyper-converged infrastructure (HCI). The main characteristics of the solution are reported in the following paragraphs.

Choosing and customizing your hardware

The customer was able to customize the hardware solution according to their needs, going to configure the processor, memory, storage and features of network adapters, respecting the supplier's compatibility matrices.

Figure 2 - Hardware composition of the Azure Stack HCI solution

There are several hardware vendors that offer suitable solutions to run Azure Stack HCI and can be consulted by accessing this link. The choice is wide and falls on more than 200 solutions of more than 20 different partners. Azure Stack HCI requires hardware that is specifically tested and validated by various vendors.

Dedicated and specific operating system

The operating system of the solution Azure Stack HCI is a specific operating system with a simplified composition and more up-to-date components than Windows Server. Roles that are not required by the solution are not included in this operating system, but there is the latest hypervisor also used in Azure environment, with software-defined networking and storage technologies optimized for virtualization.

The local user interface is minimal and is designed to be managed remotely.

Figure 3 - Azure Stack HCI OS interface

Disaster recovery and failover of virtual machines

The customer also took advantage of the possibility of creating a stretched cluster to extend their cluster Azure Stack HCI, in the specific case in two different buildings. This functionality is based on storage replication (synchronous in this scenario) contemplating encryption, local site resilience and automatic failover of virtual machines in the event of a disaster.

Figure 4 – Stretched cluster dell’architettura hyper-converged di Azure Stack HCI

Updates of the entire solution stack (full-stack updates)

To reduce the complexity and operational costs of the solution update process, the customer can start in Azure Stack HCI the process that involves the full-stack upgrade (Firmware / driver along with the operating system) directly from Windows Admin Center.

Figure 5 - Solution updates of the Dell EMC branded Azure Stack HCI solution

Azure Hybrid Service: familiarity in management and operation

The customer is able to manage their infrastructure based on Azure Stack HCI in a simple way and without adopting specific software tools, as if it were an extension of the public cloud, thanks to the features mentioned in the following paragraphs.

Native integration in Azure

Azure Stack HCI natively integrates with Azure services and Azure Resource Manager (ARM). No agent is required for this integration, but Azure Arc is integrated directly into the operating system. This allows you to view, direct from the Azure Portal, the cluster Azure Stack HCI on-premises exactly like an Azure resource.

Figure 6 - Azure Stack HCI integration into Azure

By integrating with Azure Resource Manager, the customer can take advantage of the following benefits of Azure-based management:

Adopting Standard Azure Resource Manager-Based Constructs (ARM)
Classification of Clusters with Tags
Organizing Clusters in Resource Groups
Viewing all clusters Azure Stack HCI in one centralized view
Managing access using Azure Identity Access Management (IAM)

Furthermore, from the Azure Stack HCI resource you can locate, add, modify or remove extensions, thanks to which you can easily access the management features.

Figure 7 - Azure Stack HCI management capabilities

Arc-enabled VM management

In addition to managing the cluster, the customer can also use Azure Arc to provision and manage virtual machines running on Azure Stack HCI, directly from the Azure portal. Virtual machines and their associated resources (images, disks, and network) are projected into ARM as separate resources using a new multi-platform technology called Arc Resource Bridge.

In this way you can:

achieve consistent management between cloud resources and Azure Stack HCI resources;
automate virtual machine deployments using ARM templates;
guarantee self-service access thanks to Azure RBAC support.

Figure 8 - Features provided by Azure Arc integration for Azure Stack HCI VMs

Azure Backup and Azure Site Recovery

Azure Stack HCI supports Azure Backup and Azure Site Recovery. With Microsoft Azure Backup Server (MABS) the customer backs up hosts and active virtual machines in Azure Stack HCI. Furthermore, using Azure Site Recovery it is possible to activate the replication of virtual machines from Azure Stack HCI to Azure, to create specific disaster recovery scenarios.

Infrastructure monitor with Azure Monitor Insights for Azure Stack HCI

Thanks to the solution Azure Stack HCI Insights the customer is able to consult detailed information on integrity, on the performance and use of Azure Stack HCI clusters connected to Azure and registered for related monitoring. Azure Stack HCI Insights stores its data in a Log Analytics workspace, thus having the possibility to use powerful aggregations and filters to better analyze the data collected over time. You have the option of viewing the monitor data of a single cluster from the Azure Stack HCI resource page or you can use Azure Monitor to obtain an aggregate view of multiple Azure Stack HCI clusters with an overview of the health of the cluster, the state of nodes and virtual machines (CPU, memory and storage consumption), performance metrics and more. This is the same data also provided by Windows Admin Center, but designed to scale up to 500 cluster at the same time.

Figure 9 - Azure Monitor Insights control panel for Azure Stack HCI

Azure benefit for Windows Server

Microsoft offers special benefits when deploying Windows Server in Azure environment, and the same benefits are also available on Azure Stack HCI.

Figure 10 – Azure benefit for Windows Server

Azure Stack HCI allows you to:

Deploy virtual machines with Windows Server 2022 Azure Datacenter edition, which offers specific features not available in the classic Standard and Datacenter editions. To learn more about the features available in this edition, you can consult this article.
Get extended security updates for free, just like in Azure. This is true for both Windows Server 2008 / R2, both for Windows Server 2012 / R2, in addition to the corresponding versions of SQL Server.
Obtain the license and activate the Windows Server machines as in Azure. Azure Stack HCI as well as allowing you to use your own Datacenter license to enable automatic activation of virtual machines (Automatic VM Activation – AVMA), provides the option to pay the Windows Server license for guest systems through your Azure subscription, just like in Azure environment.

Dedicated Azure Support Team

Azure Stack HCI is in effect an Azure solution, therefore the customer can take advantage of Azure support with the following characteristics:

You can easily request technical support directly from the Azure portal.
Support will be provided by a new team of experts dedicated to supporting the solution Azure Stack HCI.
You can choose from different support plans, depending on your needs.

Infrastructure innovation and new evolved scenarios

In the Azure Stack HCI environment, in addition to running virtual machines, you can activate Azure Kubernetes Service (AKS) and Azure Virtual Desktop.

Azure Kubernetes Service in Azure Stack HCI

This on-premises AKS implementation scenario allows you to automate the large-scale execution of modern applications based on micro-services. Thanks to Azure Stack HCI, the adoption of these container-based application architectures can be hosted directly in your own datacenter, adopting the same Kubernetes management experience that you have with the managed service present in the Azure public cloud.

Figure 11 - AKS overview on Azure Stack HCI

For more information, you can consult the article Azure Kubernetes Service in an Azure Stack HCI environment.

Azure Virtual Desktop for Azure Stack HCI

In situations where applications are sensitive to latency, such as video editing, or scenarios where users need to take advantage of a legacy system present on-premises that cannot be easily reached, Azure Virtual Desktop adds a new hybrid option thanks to Azure Stack HCI. Azure Virtual Desktop for Azure Stack HCI uses the same cloud management plan as regular Azure Virtual Desktop, but it allows you to create session host pools using virtual machines running on Azure Stack HCI. These virtual machines can run Windows 10 and/or Windows 11 Enterprise multi-session. By placing desktops closer to users, it is possible to enable direct access with low latency and without round trip.

Conclusions

Microsoft operates one of the largest data centers in the world and is making large investments to bring the experience gained and the innovation of the cloud to Azure Stack HCI. This customer, relying on Azure Stack HCI is taking advantage of a subscription service that receives regular feature updates, with the important goal of being able to exploit the technology tested on a large scale in the cloud on-premises. Furthermore, is able to manage the resources of its environment in a unified way and have a continuous innovation of its hybrid infrastructure.

Azure Stack HCI: the constantly evolving hyper-converged solution – edition of November 2021

New workloads and new benefits

The result that Microsoft intends to pursue with the Azure Stack HCI infrastructure is to be able to run the same workloads as the public cloud in an on-premises environment with the same advantages. To achieve this, Microsoft is bringing the most popular Azure workloads to Azure Stack HCI.

Starting last year, the Azure Kubernetes Service orchestrator can be activated on Azure Stack HCI (AKS), which allows you to automate the distribution and management of containerized applications in an on-premises environment just like in Azure. In addition to being able to run Windows and Linux apps in container, AKS makes the infrastructure available to run selected services of the Azure platform (PaaS) on Azure Stack HCI.

The important news announced in this area are the following.

Figure 1 - New Azure workloads and new benefits in Azure Stack HCI

Azure Virtual Desktop for Azure Stack HCI (preview)

By activating Azure Virtual Desktop in the public cloud, users can access their desktops and applications from anywhere, taking advantage of the familiarity and compatibility guaranteed by Windows 10 and Windows 11. Azure Virtual Desktop is a service hosted and managed by Microsoft, which does not require the configuration of a complex VDI infrastructure.

However, there are situations where applications are sensitive to latency, such as video editing, or scenarios where users need to take advantage of a legacy system present on-premises that cannot be easily reached. To allow you to better deal with situations of this type, Azure Virtual Desktop adds a new hybrid option thanks to Azure Stack HCI.

Azure Virtual Desktop for Azure Stack HCI uses the same cloud management plan as regular Azure Virtual Desktop, but it allows you to create session host pools using virtual machines running on Azure Stack HCI. These virtual machines can run Windows 10 and/or Windows 11 Enterprise multi-session. By placing desktops closer to users, it is possible to enable direct access with low latency and without round trip, using a technology called RDP Shortpath.

Azure benefit for Windows Server

Microsoft offers special benefits when deploying Windows Server in Azure environment and the same benefits, by the end of this year, will also be available on Azure Stack HCI.

First of all, when deploying virtual machines with Windows Server 2022, even in the Azure Stack HCI environment it is possible to activate the Azure Datacenter edition which offers specific features not available in the classic Standard and Datacenter editions. To learn more about the features available in this edition, you can consult this article.

Furthermore, Azure Stack HCI version 21H2 allows you to:

Get extended security updates for free, just like in Azure. This applies to Windows Server 2008 / R2 and will soon apply to Windows Server 2012 / R2 as well when we reach end of support, in addition to the corresponding versions of SQL Server.
Obtain the license and activate the Windows Server machines as in Azure. Azure Stack HCI as well as allowing you to use your own Datacenter license to enable automatic activation of virtual machines (Automatic VM Activation – AVMA), provides the option to pay the Windows Server license for guest systems through your Azure subscription, just like in Azure environment.

Infrastructure innovation

Microsoft manages some of the world's largest data centers and wants to bring the experience gained and innovation of the cloud to Azure Stack HCI. For these reasons, Azure Stack HCI is a subscription service that receives regular feature updates with the important goal of being able to take advantage on-premises of the technology tested on a large scale in the cloud.

Figure 2 – Infrastructure innovation in Azure Stack HCI

Thanks to the release of the latest update, known as “version 21H2” or as a "feature update 21H2", the following new features are introduced:

Quick restart management with Kernel Soft Reboot: improves restart performance, skipping the pre-boot sequence and self-test when turning on the hardware. This also reduces the overall cluster upgrade time (available only on Azure Stack HCI Integrated Systems).
Use of GPUs with clustered VMs: provides GPU acceleration to workloads running on clustered VMs. Ideal for AI / ML workloads.
Dynamic CPU compatibility mode: the processor compatibility mode has been updated to take full advantage of all the features of the processors in a cluster environment. In fact,, it is possible to combine different generations of processors in the same cluster with minimal degradation. The cluster intelligently calculates the largest common subset of processor functionality that can be exposed to virtual machines.
Storage thin provisioning: improves storage efficiency and simplifies management through thin provisioning.
Network ATC: simplifies host network configuration management.
Adjustable storage repair speed: greater control over the data re-synchronization process.
Support for nested virtualization with AMD processors: better flexibility to create test and evaluation environments thanks to the possibility of activating nested virtualization even in the presence of AMD processors.
Secured-Core Server: offers transversal security on hardware and firmware, integrated into the functionalities of the operating system, that can help protect servers from advanced threats.

New management features

Another result you want to achieve with Azure Stack HCI is to be able to manage your infrastructure as if it were an extension of the public cloud. Azure Stack HCI integrates natively with Azure Resource Manager and this allows you to project the cluster as a resource in the Azure portal. This allows you to leverage the same processes across all environments and manage Azure Stack HCI resources just like cloud resources.

Figure 3 – New Azure Stack HCI management features

Host server Arc-enabled and extensions

From the Azure Stack HCI resource you can locate, add, modify or remove extensions, thanks to which you can easily access the management features. With the availability of Azure Stack HCI version 21H2 the cluster will automatically enable host servers to Arc, at the time of registration, to be able to use the available extensions right away.

Arc-enabled VM management (preview)

In addition to managing the cluster, Azure Arc can now also be used to provision and manage virtual machines running on Azure Stack HCI, directly from the Azure portal. Virtual machines and their associated resources (images, disks, and network) are projected into ARM as separate resources using a new cross-platform technology called Arc Resource Bridge.

In this way you can:

achieve consistent management between cloud resources and Azure Stack HCI resources;
automate virtual machine deployments using ARM templates;
guarantee self-service access thanks to Azure RBAC support.

Azure Backup and Azure Site Recovery

With Azure Stack HCI version 21H2 official support for Azure Backup and Azure Site Recovery was introduced. With MABS v3 UR2 or later it is possible to back up hosts and active virtual machines in Azure Stack HCI. Furthermore, with Azure Site Recovery it is possible to replicate virtual machines from Azure Stack HCI to Azure and activate disaster recovery scenarios.

Conclusions

Thanks to constant improvement, the continuous introduction of new features and the inclusion of new usage scenarios, the proposition for hyper-converged scenarios is increasingly complete, integrated and performing. Azure Stack HCI integrates perfectly with the existing on-premises environment and offers an important added value: the ability to connect Azure Stack HCI with other Azure services to obtain a hybrid hyper-converged solution. This aspect in particular strongly differentiates it from other competitors who offer solutions in this area.

Azure Kubernetes Service in an Azure Stack HCI environment

The hyper-converged Azure Stack HCI solution allows you to activate the Azure Kubernetes Service orchestrator in an on-premises environment (AKS) for running containerized applications at scale. This article explores how Azure Kubernetes in Azure Stack HCI environment offers the possibility of hosting Linux and Windows containers in your datacenter, going to explore the main benefits of this solution.

Before going into the specifics of AKS in the Azure Stack environment, a summary of the solutions involved is reported.

What is Kubernetes?

Kubernetes, also known as "k8s", provides automated orchestration of containers, improving its reliability and reducing the time and resources required in the DevOps field, through:

Generally simpler deployments that allow automatic implementations and rollbacks.
Better application management with the ability to monitor the status of services to avoid implementation errors. In fact,, the various features include service integrity checks, with the ability to restart containers that are not running or that are blocked, allowing to advertise to clients only the services that have started correctly.
Ability to scale automatically based on usage and, exactly the same as for containers, manage the cluster environment in a declarative manner, allowing version-controlled and easily replicable configuration.

Figure 1 – Kubernetes cluster with related architecture components

What is Azure Kubernetes Service (AKS)?

Azure Kubernetes Service (AKS) is the fully managed Azure service that allows the activation of a Kubernetes cluster, ideal for simplifying the deployment and management of microservices-based architectures. Thanks to the features offered by AKS it is possible to scale automatically according to the use, use controls to ensure the integrity of the services, implement load balancing policies and manage secrets. The use of this managed service is integrated with the container development and deployment pipelines.

Figure 2 - Azure Kubernetes Service architecture example (AKS)

What is Azure Stack HCI?

Azure Stack HCI is the solution that allows you to create a hyper-converged infrastructure (HCI) for the execution of workloads in an on-premises environment and which provides for a strategic connection to Azure services. This is a hyper-converged infrastructure (HCI), where different hardware components are removed, substitutes from the software, able to combine the layer of compute, storage and network in one solution. In this way there is a transition from a traditional "three tier" infrastructure, composed of network switches, appliance, physical systems with onboard hypervisors, storage fabric and SAN, toward hyper-converged infrastructure (HCI).

Figure 3 – "Three Tier" Infrastructure vs Hyper-Converged Infrastructure (HCI)

What is AKS in Azure Stack HCI?

AKS in the Azure Stack HCI environment is a Microsoft implementation of AKS, which automates the deployment and management of containerized applications.

Microsoft, after introducing AKS as a service in Azure, has extended its availability also to on-premises environments. However, there are some important differences:

In Azure, Microsoft manages the control plane of each AKS cluster. Furthermore, the cluster nodes (management node and worker node) run on Azure virtual machines or on Azure virtual machine scale sets.
In an on-premises environment , the customer manages the entire environment, where the AKS cluster nodes are running on virtual machines hosted on the hyper-converged infrastructure.

AKS architecture on Azure Stack HCI

The implementation of AKS in Azure Stack HCI consists of two types of clusters:

A management cluster of AKS. This cluster acts as a dedicated control plane for managing Kubernetes clusters running on the hyper-converged platform. This cluster consists of Linux virtual machines, that host Kubernetes system components such as API servers and load balancers.
One or more Kubernetes clusters. These clusters consist of control nodes and worker nodes. Control nodes are implemented as Linux virtual machines, with API server and load balancers that satisfy the requests of Azure Stack HCI users. Workloads are distributed on Linux or Windows OS-based worker nodes.

Figure 4 - AKS architecture on Azure Stack HCI

Each Kubernetes cluster runs on its own dedicated set of virtual machines, protected by hypervisor-based isolation, allowing you to securely share the same physical infrastructure even in scenarios that require workload isolation.

AKS on Azure Stack HCI supports both Linux-based and Windows-based containers. When you create a Kubernetes cluster you simply need to specify the type of container you intend to run and on the hyper-converged platform the installation procedure of the required operating system is automatically started on the nodes of the Kubernetes cluster .

Benefits of AKS on Azure Stack HCI

AKS simplifies the deployment of Kubernetes clusters by providing a layer of abstraction that can mask some of the more challenging implementation details.

Among the main benefits of AKS in the Azure Stack HCI environment we find:

Simplified deployments of containerized apps in a cluster environment. Using the Windows Admin Center you have a guided installation process of the AKS management cluster. Windows Admin Center also facilitates the installation of individual Kubernetes clusters that contain worker nodes, through an automatic installation process of all relevant software components, including management tools such as kubectl.
Ability to scale horizontally to manage computational resources, adding or removing Kubernetes cluster nodes.
Simplified management of cluster resource storage and network configurations.
Automatic updates of cluster nodes to the latest version of Kubernetes available. Microsoft manages the Windows Server and Linux images for the cluster nodes and updates them monthly.
Strategic connection, using Azure Arc, to Azure services such as: Microsoft Azure Monitor, Azure Policy, and Azure Role-Based Access Control (RBAC).
Centralized management of Kubernetes clusters and related workloads through the Azure portal, thanks to the adoption of Azure Arc for Kubernetes. Azure portal-based management also integrates traditional Kubernetes administration tools and interfaces, like the command line utility kubectl and the Kubernetes dashboard.
Managing the automatic failover of virtual machines acting as Kubernetes cluster nodes if there is a localized failure of the underlying physical components. This complements the high availability inherent in Kubernetes, able to automatically restart containers in failed state.

Conclusions

Thanks to Azure Stack HCI, the adoption of container-based application architectures can be hosted directly in your own datacenter, adopting the same Kubernetes management experience that you have with the managed service present in the Azure public cloud. The deployment process is also very simplified and intuitive. Furthermore, Azure Stack HCI allows you to further improve the agility and resilience of Kubernetes deployments in an on-premises environment.

Azure Stack HCI: disaster recovery features inherent in the solution

In the latest version ofAzure Stack HCI is included the ability to create stretched clusters to extend a cluster ofAzure Stack HCI in two different locations (rooms, buildings or even different cities). This disaster recovery solution provides storage replication (synchronous or asynchronous) and contemplates encryption, local site resilience and automatic failover of virtual machines. This article explores the possible architectures and features of the solution.

To further improve the built-in resilience in the Azure Stack HCI solution, it is possible to implement a cluster consisting of two groups of nodes, defined "stretched cluster". Each group is located in a different site and must contain a minimum of two nodes. A stretched cluster can consist of a minimum of four to sixteen physical nodes (maximum number of nodes supported by an Azure Stack HCI cluster), which must satisfy the standard hardware requirements for HCI solutions.

Figure 1 - Overview of a stretched cluster in an Azure Stack HCI hyper-converged architecture

Going into the detail of the architecture, the components and functionalities used are:

Azure Stack HCI. The minimum required version is 20H2, deployed as an Azure hybrid service and released in December 2020. This is a hyper-converged infrastructure (HCI), where different hardware components are removed, substitutes from the software, able to combine the layer of compute, storage and network in one solution.
Storage Replica. The technology included in Windows Server that allows replication of volumes between servers or between clusters for disaster recovery purposes.
Live Migration. The Hyper-V feature that allows you to easily move virtual machines (VMs) running on one Hyper-V host to another, without having downtime. This feature is useful for managing expected or scheduled downtime.
Witness resource. Witness is a mandatory component within Azure Stack HCI clusters. To implement it, you can choose an Azure Cloud Witness or a File Share Witness. Azure Cloud Witness is the recommended choice for Azure Stack HCI stretched clusters as long as all nodes have a reliable internet connection.

An Azure Stack HCI stretched cluster is based on the use of Storage Replica and it is possible to have a synchronous or asynchronous replica of the data:

Using the synchronous replication data is mirrored between sites on a low-latency network. Volumes are crash-consistent to ensure zero data loss at the file system level during a failure event. The requirement for synchronous replication applicable to stretched clusters enforces network latency of 5 ms of round trip between the two groups of nodes located in the replicated sites. Depending on the connectivity characteristics of the physical network, this constraint generally translates into approx 30-45 Km away. With this configuration, if there is a problem affecting the availability of a site, the cluster is able to automatically transfer workloads to the nodes of the site not affected by the problem to minimize potential downtime.
The asynchronous replication mirrors data between sites over network links with higher latencies, but there is no guarantee that both sites have identical copies of the data when a failure event occurs. In the presence of asynchronous replication, it is necessary to manually bring the target volumes online to the other site following a failover.

There are two types of stretched clusters: active-active and active-passive.

Figure 2 - Types of stretched clusters compared

An active site is a site that has resources and hosts roles and workloads to which clients can connect. A passive site is a site that does not dispense roles or workloads for clients, but is awaiting a failover from the active site for disaster recovery purposes.

Replication in an active-passive stretched cluster has a preferred direction, while replication in an active-active stretched cluster can take place bi-directionally from both sites.

Azure Stack HCI and Storage Replica also support data deduplication, useful to increase the usable storage capacity, identifying duplicate portions of files and archiving them only once. Starting with Windows Server 2019, deduplication is available on volumes formatted with Resilient File System (ReFS), which is the recommended file system for Azure Stack HCI. In Azure Stack HCI stretched clusters, it is recommended to enable Data Deduplication only on the nodes of the source cluster, and not on target nodes, who always receive deduplicated copies of each volume.

Conclusions

The ability to extend clusters Azure Stack HCI in two different locations allows you to implement disaster recovery architectures in a way that is fully integrated into the solution, without the need to adopt third-party products. This characteristic, combined with the ability to connect Azure Stack HCI with Azure services to achieve a hybrid hyper-converged system, makes it a complete solution, stable and reliable, able to meet the most advanced needs in hosting business critical workloads.