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.
