How Tencent Built a Massive Cloud Storage System to Power QQ Album and Beyond

In December 2017, QQ album traffic spiked dramatically, pushing storage usage close to overload limits. The System Architecture Department, a secretive group of top engineers within Tencent, was tasked with solving this crisis.

Starting in 2006, the team built the Tencent File System (TFS), a distributed storage platform designed for massive unstructured data such as photos. TFS first supported QQ space, handling daily uploads that quickly grew from millions to billions of images.

To monitor performance, the team visualized response times on a national map, turning red zones into green as optimizations took effect. By the end of 2007, the system consistently delivered sub‑3‑second load times across China.

When SNS games like QQ Farm emerged in 2009, write‑heavy workloads exposed the limits of the existing architecture. The team introduced an in‑memory write buffer (TMEM) that turned random writes into sequential disk writes, dramatically improving throughput.

Rapid user growth forced a historic cross‑city data migration from Shenzhen to multiple “one‑link” data centers in Xi’an, Hangzhou, Guangzhou, and Shanghai. The migration moved over 100 TB of data using public network links during off‑peak hours, relieving bandwidth pressure and improving availability.

To reduce storage costs for cold data, Tencent developed the Backup‑TFS (BTFS) platform based on erasure coding, lowering replica factors from three to 1.33 while preserving reliability.

As cloud services expanded, Tencent launched its own cloud storage offerings in 2013, scaling from 500 PB in 2014 to over 1 EB by 2015, and eventually supporting petabyte‑scale workloads for QQ, WeChat, Weiyun, and other products.

Recognizing the need for a cloud‑native solution, the team began designing YottaStore in 2018. YottaStore aims to manage millions of servers with a lightweight index structure, support flexible redundancy across single or multiple availability zones, and provide zero‑downtime upgrades for clusters of any size.

Since its launch, YottaStore has achieved 100 % availability in its first three months and has been used to power Tencent Cloud’s deep‑archive service, offering storage at a record low price of 0.01 CNY per GB per month.

The architects who built these systems have since become leaders in AI, server infrastructure, operations, search, CDN, and video encoding, continuing to drive innovation across Tencent’s ecosystem.