Public, private and hybrid cloud – architecture and challenges
Enterprises are increasingly looking for cloud solutions, but the concept of the “cloud” remains broad and sometimes confusing. In practice, three main models…
Enterprises are increasingly looking for cloud solutions, but the concept of the “cloud” remains broad and sometimes confusing. In practice, three main models are distinguished: public, private, and hybrid cloud. Each of them offers different possibilities in terms of flexibility, scalability, security, and regulatory compliance. Therefore, before deciding to migrate or deploy new infrastructure, it is essential to understand the technical aspects of the individual solutions and their implications for the company’s day-to-day operations.
What is a public cloud?
Public cloud is based on the infrastructure of an external provider that makes resources (computing power, storage space, network services) available on a shared basis. Using such a model can be very convenient thanks to flexible scaling and the pay-as-you-go billing model. Technically, this means managing virtual machines, containers, and often ready-made PaaS or FaaS services. From an architectural perspective, the company then focuses on creating consistent CI/CD, integrating with monitoring systems, and ensuring data security through the configuration of encryption, WAF (Web Application Firewall) systems, or IAM (Identity and Access Management) policies. However, the main challenges of the public cloud include limited control over the physical hardware layer, concerns about data sovereignty (especially if the provider does not have a data center in Poland), and potential cost increases under long-term and intensive workloads.
What is a private cloud?
Private cloud, on the other hand, is an environment dedicated exclusively to a single organization, which translates into full control over the physical infrastructure and configuration. Technically, this means independently deploying a virtualization layer (e.g. KVM, VMware, OpenStack), SDN (Software-Defined Networking) mechanisms, or automation tools (Ansible, Terraform) in its own or rented (colocated) data center. In the context of Polish law, this is often the most suitable model for entities operating in regulated sectors, as it enables precise determination of the location of servers and data processing processes. The disadvantage, however, can be the high initial CAPEX (Capital Expenditure) associated with purchasing hardware, as well as the need to have specialists to manage the environment. Private cloud can also be rented from an external provider that provides dedicated physical infrastructure and support in maintaining it. In such a model, initial investment expenditure (CAPEX) is significantly reduced, as it is replaced by regular operating costs (OPEX) in the form of subscription fees and managed services.
What is a hybrid cloud?
Hybrid cloud is a compromise combining both of the approaches described above. Companies often keep critical systems in a private data center while gaining flexibility by periodically moving part of their workload to the public cloud. From a technical perspective, this requires solid network integration (VPN, MPLS, SD-WAN) and consistent orchestration tools (e.g. Kubernetes in hybrid mode, with nodes both on-premises and in the cloud). Securing data in transit is also crucial in order to meet the requirements arising from GDPR and Polish data protection laws. In a hybrid cloud, an additional challenge arises in terms of scaling and monitoring: it is necessary to oversee several environments simultaneously, which requires an appropriate automation plan and DevOps tools.
The table presents the differences between cloud solutions
| Criterion | Public Cloud | Private Cloud | Hybrid Cloud |
| Control over infrastructure | Limited – the main infrastructure is managed by the public cloud provider. | Full – the organization independently decides on every aspect of the configuration and server location. | Partial – full control over private resources, limited control over the public part. |
| Server location | The provider’s data center facilities, which may be located in different places around the world (depending on service availability). | Own (on-premises) or rented, with full ability to specify the country and exact location of data centers (important in regulated sectors). | Depends on the configuration – some resources are located in the private cloud and some in the public cloud. |
| Scalability | Very high and flexible – resources can be dynamically purchased or released. | Limited by the availability of purchased/owned hardware, but with the ability to precisely control expansion. | Flexible – some workloads can be moved to the public cloud if private resources are insufficient. |
| Competency requirements | Knowledge of how to manage public services and negotiate contract terms (SLA, security) is necessary. | The need to have (or hire) specialists to manage infrastructure and virtualization software (e.g. KVM, VMware, OpenStack). | Competencies from both worlds (public and private cloud) are required, along with appropriate tools for their integration. |
| Applications | A good option for companies looking for a fast, scalable, and universal platform (e.g. startups, testing projects). | Sectors requiring full control over data (e.g. medical, financial, administration) or companies with strictly defined security and location requirements. | Enterprises that want to combine the benefits of private and public cloud – e.g. periodically increasing computing power. |
Summary
In summary, choosing the right cloud always depends on specific business, technological, and regulatory needs. In many cases, both the law and internal regulations require a clear definition of where data is processed and which entities may have access to it. Therefore, in the following articles, we will take a closer look at the details related to costs (CAPEX and OPEX), data location in the context of Polish regulations, and information security in practice.
