What CDN Architecture Evolution Says About the Future of IT and Storage

CDN Architecture Evolution

Early CDN deployments at Lanjun used a second‑generation architecture built on SQUID. The framework exposed modular hook points so that developers could implement tens of thousands of customizations. The deployment model was a single‑machine box equipped with a gigabit NIC and SATA HDDs.

As download and video traffic grew, the architecture migrated to 10 GbE NICs and clustered deployments. The core switched to NGINX, and storage became the primary performance bottleneck.

Intensified market competition forced CDN providers to adopt layered deployment models and more specialized designs. Recent hardware introductions—SSD drives and 25 Gb/100 Gb NICs—have alleviated both disk‑I/O and network‑I/O limits. Consequently, modern CDN stacks increasingly rely on zero‑copy and kernel‑bypass technologies such as DMA, RDMA, SPDK and DPDK.

Although the underlying stack is largely open‑source, extensive customizations are required to satisfy diverse client requirements, cost constraints, and rapid feature cycles. In practice, a CDN architecture can be expressed as:

Open‑source foundation (e.g., SQUID, NGINX, XFS, XCACHE)

Deep, per‑customer customisation of caching, storage separation, and network handling

Storage Market Outlook

The industry is moving toward NVMe‑based storage as the dominant form factor. Key drivers include:

PCIe bandwidth growth : each new PCIe generation doubles per‑lane bandwidth. Over the next five years PCIe is expected to progress from Gen3 to Gen6, delivering roughly eight times the bandwidth of today’s Gen3. SATA interfaces are not expected to improve, widening the performance gap to NVMe.

NVMe capacity and performance : current production devices range from 2 TB to 8 TB. Roadmaps indicate 16 TB–32 TB devices within a few years. QLC and PLC NAND SSDs provide a cost‑per‑GB balance for large‑capacity deployments.

Emerging storage media : NAND flash will become the next I/O bottleneck as PCIe speeds increase (e.g., Gen4 servers). Storage Class Memory (SCM) is projected to replace NAND as the primary local storage engine, offering higher bandwidth and lower latency.

High‑Performance Storage System XFS – SACC 2020 Presentation

At the 12th China System Architect Conference (SACC 2020), Zhou Chaoyong will present “High‑Performance Storage System XFS Architecture Practice.” The talk will cover:

The design of XFS for small‑file, directory‑aware workloads.

How XFS originated from CDN cache storage requirements.

Advantages of XFS in modern storage stacks, including scalability, metadata handling, and integration with zero‑copy I/O paths.