Hybrid cloud: definition and principles
What is hybrid cloud?
Hybrid cloud refers to a IT environment that combines on-premise infrastructure and public cloud, with unified orchestration and management. Your applications and data are distributed between your private datacenters and cloud services such as Azure, AWS or Google Cloud for example, while communicating via secure network connections. Hybrid multi-cloud is possible, you can very well combine Azure and AWS services in addition to your on-premise infrastructure to combine control and cloud agility.
Key characteristics of a true hybrid environment include the orchestral coexistence of resources, a secure network connection, unified management, and the mobility of workloads between environments.
Attention: simply having a server on your premises and an Azure subscription does not constitute a functional hybrid cloud in the Microsoft environment. Without orchestration or unified management, you are combining two distinct environments with their respective complexity.
The three cloud deployment models
Three approaches are possible in relation to the cloud:
An approach Pure on-premise where all the infrastructure is kept in your data centers. You maintain total control and complete sovereignty, but assume heavy investments to avoid infrastructure obsolescence and limited agility. This approach is suitable for highly regulated sectors with strong sovereignty constraints.
An approach Pure public cloud (cloud only) which consists of migrating all your resources to Azure or AWS. You gain agility, scalability, and eliminate physical infrastructure management, but you are completely dependent on your cloud provider and the costs can be high if the service is poorly optimized. This model appeals to startups and cloud-native organizations.
Finally, the approach Hybrid cloud combines on-premise and cloud approaches according to an optimized placement logic. This approach offers maximum flexibility and allows for a gradual transition but generates increased management complexity.
There is no universal “best model.” The choice depends on your organizational context, regulatory constraints, and existing infrastructure.
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Why is hybrid cloud so common?
Market data confirms this fundamental trend: according to Gartner, 90% of companies plan to adopt a hybrid cloud strategy by 2027. This massive projection is explained by several structural factors.
The gradual transition drastically reduces risks. Migrating an entire information system at once is a dangerous bet. The hybrid approach makes it possible to modernise in stages, by validating each phase.
Legacy applications pose real constraints. Some critical applications cannot technically migrate to the cloud or at a prohibitive cost. Keeping them on-premise while you modernize the rest is the most rational decision.
Regulatory requirements impose specific locations. The GDPR, HDS health requirements or banking sector constraints sometimes require certain data to be maintained in specific datacenters.
Your recent investments deserve to be amortized. If you renewed your infrastructure two years ago, throwing it away would destroy value. The hybrid makes it possible to make these investments profitable while preparing for the future.
The benefits of hybrid cloud for Microsoft organizations
Flexibility: choosing the best location for each workload
The main advantage of the hybrid lies in its ability to optimize the placement of each application according to performance, cost, compliance or criticality criteria.
Here is a typical smart breakdown:
- Legacy critical applications : On-premise (difficult to migrate)
- Modern business applications : Azure (agility, scalability)
- Regulated sensitive data : On-premise or sovereign cloud (compliance)
- Analytical data and AI : Azure (computing power, coupling with Power BI to transform your data)
- Dev/test environments : Azure DevOps (instant provisioning, optimized costs)
Thus, a medium-sized bank can thus maintain its core banking system on-premise for regulation, while deploying its mobile applications and analysis tools on Azure to benefit from agility.
Gradual transition: modernising without a big bang
The “big bang” approach combines risks: potential interruptions, maximum technical complexity, increased resistance to change. The hybrid cloud allows migration in successive waves.
You first migrate your dev/test environments (where the risk is low and allows learning), then the non-critical applications (to validate procedures), then the critical applications gradually and finally you assess whether certain loads should remain on-premise permanently.
This progressiveness reduces risks, allows for continuous learning, and provides the opportunity to go back at each stage. The construction of a clear digital roadmap precisely structures this approach.
Compliance with constraints: compliance and data sovereignty
Regulatory constraints are often the main obstacle to a complete cloud migration. The hybrid transforms this constraint into an opportunity.
For the RGPD, some sensitive data must remain in the EU. Azure offers Datacenters in Paris and Marseille, but for more stringent requirements, on-premise maintenance may be necessary.
In the health sector, patient data requires HDS certified hosting. A hospital can keep patient records on-premise while using Azure for its administrative applications.
The banking sector often keeps critical transactions on-premise for regulation, while digital customer services run in the cloud for scalability.
Azure has more than 100 compliance certifications (ISO 27001, SOC 2, HDS), making it easy to demonstrate compliance related to data sovereignty for the cloud parts of your infrastructure.
Microsoft tools for the hybrid cloud
Azure Arc: Extend Azure Everywhere
Azure Arc is the cornerstone of Microsoft's hybrid strategy. This service brings the Azure experience to your on-premise and even multi-cloud resources.
Concretely, Azure Arc allows you to manage your Windows and Linux servers (physical or virtual), your Kubernetes clusters, your on-premise SQL Server instances and your applications from the Azure portal, regardless of their location.
The operational benefits are considerable:
- Unified management : a single portal to manage everything, eliminating multiple interfaces.
- Coherent governance : Azure Policy applies uniformly everywhere.
- Centralized security : Microsoft Defender for Cloud protects your on-premise servers as well as your Azure resources.
- Unified monitoring : Azure Monitor collects metrics from across your infrastructure.
Thus, it is possible to manage 200 on-premise servers and 50 Azure machines from the same portal, with the same tools and processes.
Azure Stack: Azure in your data center
Azure Stack takes the opposite approach: you Deploy Azure in your data centers. Microsoft offers several versions:
- Azure Stack HCI: hyper-converged infrastructure for virtualization and storage
- Azure Stack Hub: a set of Azure services that can be deployed on-premise,
- Azure Stack Edge: compact servers for remote sites.
The fundamental difference: Azure Arc manages your existing servers from Azure, while Azure Stack installs a physical Azure infrastructure on your premises.
Azure Stack remains less common than Arc due to its cost and complexity, but meets the specific needs of organizations that absolutely cannot use the public cloud.
Hybrid connectivity: VPN, ExpressRoute, and Azure AD Connect
Network connectivity and identity unification are the technical foundations of a functional Azure hybrid environment.
Connectivity is at the level of network where 2 options are possible:
- Azure VPN Gateway Establishes secure site-to-site VPN connections over the internet. It is an economical solution to start up or for modest needs.
- Azure ExpressRoute creates a dedicated private connection without going through the public Internet. It is a more reliable and faster solution but also more expensive. ExpressRoute is ideal for critical loads that require high availability.
Connectivity at the level of The identity of users is made thanks to Entra ID Connect (Azure AD Connect) that synchronizes your on-premise Active Directory with Entra ID in the cloud. Your users have a unique identity that works for on-premise and cloud resources.
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Hybrid cloud challenges (and how to overcome them)
Increased management complexity
Managing two environments inherently creates more complexity only one. This reality should not be minimized.
With the hybrid cloud, there are two network infrastructures to maintain, two different management models (cloud IaaS and traditional infrastructure), necessary cloud skills and monitoring covering several environments.
Among the strategies to be deployed to control this complexity, we can mention:
- Azure Arc which drastically reduces the load by unifying hybrid cloud management,
- Continuing education of your IT teams on the cloud,
- Automation via Infrastructure as Code to standardize deployments,
- Support by an expert partner to speed up the learning curve and avoid classic pitfalls.
The complexity is real, but it becomes manageable with the right tools and the right expertise.
Costs: avoid unpleasant surprises
The major financial risk consists in cumulate on-premise and cloud costs without optimization, turning the hybrid into a double budget penalty.
This is especially the case when you want to maintain too much on-premise infrastructure by inertia (“just in case”), or when you underestimate cloud costs (with resources active 24/7 without optimization).
Some best practices:
- Calculate the full TCO (Total Cost of Ownership), including staff, training, connectivity. Not just the price shown on Azure.
- Streamline on-premise progressively : really decommission the infrastructure freed up as migrations take place.
- Optimize the cloud rigorously : by using Azure reservations for predictable loads (up to 70% savings) and by turning off unused resources.
Well architected, the hybrid can even optimize your costs: stable loads on amortized infrastructure, peaks and new projects in the cloud on a pay-per-use basis.
Security: ensuring consistency between on-premise and cloud
The attack surface is expanding with the hybrid: poorly secured network connections, inconsistent security policies, and approximate identity management. You need to secure two environments and The connections that connect them.
To avoid security breaches:
- Adopt Zero Trust : a systematic verification of each access,
- Implement MFA everywhere via Entra ID,
- Do systematic encryption data in transit and at rest
- Use Microsoft Defender for Cloud for unified security,
- Create policies that are consistent with Azure Policy everywhere via Arc.
With the right governance tools, hybrid security becomes manageable and can even exceed that of many aging on-premise environments.
Architecting a Microsoft hybrid environment
The principles of hybrid architecture
A robust hybrid cloud architecture is based on seven fundamental principles:
- Unified identity with Azure AD Connect synchronizing AD on-premise and Microsoft Entra ID.
- Secure connectivity via VPN Gateway or ExpressRoute with redundancy.
- Unified management by Azure Arc to manage all your resources.
- Zero Trust Security with systematic verification.
- Unified monitoring via Azure Monitor.
- Automation via IaC with Azure Resource Manager, Bicep, or Terraform.
- Disaster Recovery (Disaster recovery) with Azure Site Recovery orchestrating replication.
These principles, applied methodically, transform a disparate assembly into a coherent and efficient hybrid environment.
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Avoid the classic hybrid pitfalls
There are generally five recurring mistakes to anticipate with the hybrid cloud.
First of all, adopt the hybrid by default without a strategy. You need to define whether the hybrid is your final setup or a transition stage.
You also don't have to underestimate complexity : invest in training, tools and even support to save time and impact in managing both environments.
Then the network connection sizing is often a problem. A VPN that is too slow for your real needs can have a major impact on operations. You should pay attention to sizing from the start.
Of identities that are not synchronized can also cause difficulties with duplicate accounts, desynchronizations or even security breaches. Azure AD Connect needs to be rigorously configured and monitored.
Finally, the excessive on-premise conservation by inertia is also a problem because the hybrid becomes expensive without optimization. You must regularly review what should actually remain on-premise with objective criteria.
Get support for a successful hybrid
The successful hybrid requires technical expertise but also strategic vision. Askware intervenes throughout the value chain from audit of the existing to analyze your current infrastructure and identify the constraints on a hybrid infrastructure in terms of your business.
Askware is also involved in the cloud strategy definition with the migration roadmap and TCO calculation, the hybrid environment architecture (network design, identity strategy, Zero Trust security, hybrid multi-cloud) and the operational implementation with the deployment of Azure Arc, the configuration of hybrid connectivity, and the gradual migration.
We Let's form the teams on cloud technologies, hybrid tools, governance and continuous optimization with cost monitoring and architecture evolution.
Our added value lies in combination of strategic vision and technical execution, with deep expertise in the Microsoft ecosystem.
The hybrid cloud is neither a compromise nor a migration failure, it is a deliberate strategy combining on-premise control and cloud agility. For Microsoft organizations in transition, with existing infrastructure or regulatory constraints, hybrid often represents the most rational approach.
Succeeding with the hybrid requires a clear strategy, a well-thought-out architecture, and rigorous management to avoid multiple complexity and cumulative costs. The hybrid can be a transition phase of 2 to 5 years or the definitive target state. The main thing is to choose consciously and not by default.
Askware helps you define your cloud strategy, assess the relevance of the hybrid for your context, architect your Microsoft hybrid environment and manage the transition methodically.
Ready to define your hybrid cloud strategy? Contact our experts for an audit of your infrastructure and let's build together the optimal architecture for your organization.
