At its simplest, a data center is a physical facility that organisations use to house their critical applications and data. A data center's design is based on a network of computing and storage resources that enable the delivery of shared applications and data. The key components of a data center design include routers, switches, firewalls, storage systems, servers, and application-delivery controllers.
Modern data centers are very different than they were just a short time ago. Infrastructure has shifted from traditional on-premises physical servers to virtual networks that support applications and workloads across pools of physical infrastructure and into a multicloud environment.
In this era, data exists and is connected across multiple data centers, the edge, and public and private clouds. The data center must be able to communicate across these multiple sites, both on-premises and in the cloud. Even the public cloud is a collection of data centers. When applications are hosted in the cloud, they are using data center resources from the cloud provider.
In the world of enterprise IT, data centers are designed to support business applications and activities that include:
Data center design includes routers, switches, firewalls, storage systems, servers, and application delivery controllers. Because these components store and manage business-critical data and applications, data center security is critical in data center design. Together, they provide:
Network infrastructure. This connects servers (physical and virtualised), data center services, storage, and external connectivity to end-user locations.
Storage infrastructure. Data is the fuel of the modern data center. Storage systems are used to hold this valuable commodity.
Computing resources. Applications are the engines of a data center. These servers provide the processing, memory, local storage, and network connectivity that drive applications.
Data center services are typically deployed to protect the performance and integrity of the core data center components.
Network security appliances. These include firewall and intrusion protection to safeguard the data center.
Application delivery assurance. To maintain application performance, these mechanisms provide application resiliency and availability via automatic failover and load balancing.
Data center components require significant infrastructure to support the center's hardware and software. These include power subsystems, uninterruptible power supplies (UPS), ventilation, cooling systems, fire suppression, backup generators, and connections to external networks.
The most widely adopted standard for data center design and data center infrastructure is ANSI/TIA-942. It includes standards for ANSI/TIA-942-ready certification, which ensures compliance with one of four categories of data center tiers rated for levels of redundancy and fault tolerance.
Tier 1: Basic site infrastructure. A Tier 1 data center offers limited protection against physical events. It has single-capacity components and a single, nonredundant distribution path.
Tier 2: Redundant-capacity component site infrastructure. This data center offers improved protection against physical events. It has redundant-capacity components and a single, nonredundant distribution path.
Tier 3: Concurrently maintainable site infrastructure. This data center protects against virtually all physical events, providing redundant-capacity components and multiple independent distribution paths. Each component can be removed or replaced without disrupting services to end users.
Tier 4: Fault-tolerant site infrastructure. This data center provides the highest levels of fault tolerance and redundancy. Redundant-capacity components and multiple independent distribution paths enable concurrent maintainability and one fault anywhere in the installation without causing downtime.
Many types of data centers and service models are available. Their classification depends on whether they are owned by one or many organisations, how they fit (if they fit) into the topology of other data centers, what technologies they use for computing and storage, and even their energy efficiency. There are four main types of data centers:
These are built, owned, and operated by companies and are optimised for their end users. Most often they are housed on the corporate campus.
These data centers are managed by a third party (or a managed services provider) on behalf of a company. The company leases the equipment and infrastructure instead of buying it.
In colocation ("colo") data centers, a company rents space within a data center owned by others and located off company premises. The colocation data center hosts the infrastructure: building, cooling, bandwidth, security, etc., while the company provides and manages the components, including servers, storage, and firewalls.
In this off-premises form of data center, data and applications are hosted by a cloud services provider such as Amazon Web Services (AWS), Microsoft (Azure), or IBM Cloud or other public cloud provider.
Computing infrastructure has experienced three macro waves of evolution over the last 65 years:
This evolution has given rise to distributed computing. This is where data and applications are distributed among disparate systems, connected and integrated by network services and interoperability standards to function as a single environment. It has meant the term data center is now used to refer to the department that has responsibility for these systems irrespective of where they are located.
Organisations can choose to build and maintain their own hybrid cloud data centers, lease space within colocation facilities (colos), consume shared compute and storage services, or use public cloud-based services. The net effect is that applications today no longer reside in just one place. They operate in multiple public and private clouds, managed offerings, and traditional environments. In this multicloud era, the data center has become vast and complex, geared to drive the ultimate user experience.