What Exactly Is a Hybrid Cloud? Definitions, Types, and Design Principles

Definition of Hybrid Cloud

According to NIST, a hybrid cloud is an IT architecture that interconnects multiple clouds, forming a unified environment.

Typical Hybrid Cloud Forms

Public‑cloud‑to‑public‑cloud mixing

Private‑cloud‑to‑private‑cloud mixing

Public‑cloud‑to‑private‑cloud mixing

Public‑cloud‑to‑traditional‑IT mixing

Hybrid Cloud vs. Multi‑Cloud

Hybrid cloud requires dedicated links (e.g., leased lines or VPN) to connect clouds, while multi‑cloud relies on a Cloud Management Platform (CMP) and OpenAPI for management without mandatory inter‑cloud links.

Analysis of Each Form

1. Public‑to‑Public Cloud

Early hybrid solutions aimed at avoiding vendor lock‑in; tools such as HashiCorp Terraform abstract infrastructure differences across providers.

2. Private‑to‑Private Cloud

Usually connects homogeneous private clouds within the same organization to reduce operational cost; heterogeneous mixes (e.g., VMware vs. OpenStack) are rare and omitted.

3. Public‑to‑Private Cloud

Current hot spot; combines the strengths of both clouds, allowing workloads to run where they are most suitable.

4. Public‑to‑Traditional IT

Although not a strict hybrid cloud by some definitions, many enterprises treat on‑premise data‑center plus public cloud as a hybrid scenario.

Key Characteristics of Hybrid Cloud Architecture

Elasticity

Hybrid clouds amplify the inherent elasticity of cloud computing, enabling rapid horizontal scaling across clouds during peak loads and automatic resource reclamation during low demand.

Scalability

Unified open APIs simplify scaling; for example, VMware vCenter MOB interfaces can be scripted for private‑cloud scaling, while Alibaba Cloud Auto‑Scaling can be declared via JSON/YAML.

Security

Security becomes more complex because multiple clouds introduce heterogeneous security products; a unified security management center is required to enforce consistent policies and to leverage public‑cloud DDoS protection, WAF, and other services.

Hybrid‑Cloud Design Goals – The “Five‑Pass” Model

The architecture aims to achieve five connectivity goals: data‑center (机房) connectivity, network connectivity, data connectivity, application connectivity, and management connectivity.

Data‑Center Connectivity : Cloud‑management platforms can dynamically relocate workloads between racks or across data‑centers based on power consumption.

Network Connectivity : SD‑WAN, dedicated lines, and VPN gateways enable seamless inter‑cloud traffic.

Data Connectivity : Enterprise‑grade sync tools (e.g., Alibaba Cloud DataSync) provide full‑ and incremental data replication between public and private clouds.

Application Connectivity : DevOps platforms and virtual nodes allow workloads to be migrated across heterogeneous clusters.

Management Connectivity : Unified APIs support centralized resource, orchestration, alarm, monitoring, and billing management.

Hybrid Cloud in the Context of “New Infrastructure”

“New infrastructure” (新基建) comprises information infrastructure (5G, IoT, satellite internet, cloud computing, blockchain), integrated infrastructure (AI‑driven services), and innovative infrastructure (research platforms). Cloud computing forms the foundation, and hybrid cloud is the prevailing architecture to meet the scalability, performance, and security demands of this new era.

Industry Outlook

Analysts such as Gartner predict that hybrid cloud will account for about 67 % of the total cloud market, and many enterprises that already operate private clouds will adopt hybrid models to leverage public‑cloud advantages while preserving existing investments.