ADR 0003: Object Storage — Tencent COS¶
Status¶
Accepted
Date¶
2026-07-24
Context¶
OVES generates and manages multiple categories of unstructured data:
- Engineering drawings, CAD files, OEM datasheets (born in China)
- AI-generated media (images, video)
- BFF article assets (hero images, attachments)
- IoT time-series cold archives (CSV dumps)
- Odoo document attachments
Current storage was split across AWS S3 (ap-east-1 Hong Kong), OneDrive, and local disks. WeDrive was evaluated but rejected.
Decision¶
Tencent COS (对象存储) is the single object storage platform.
Tiering¶
| Tier | Use Case | Retention | Price (CN) |
|---|---|---|---|
| Standard | Active data: docs, CAD, AI media, BFF assets | 0–90 days | ¥0.099/GB/month |
| Infrequent Access (IA) | Older revisions, quarterly reports | 90–365 days | ¥0.08/GB/month |
| Deep Archive | Engineering drawings, compliance records, IoT CSV dumps | 365+ days | ¥0.01/GB/month |
Lifecycle Policy¶
Standard (0d) → IA (90d) → Deep Archive (365d)
S3 Compatibility¶
COS exposes an S3-compatible API. Existing S3 SDKs require only an
endpoint_url change. Migration uses the COS Migration Tool for bulk transfer
from S3.
Rejected Alternatives¶
| Alternative | Reason for Rejection |
|---|---|
| AWS S3 (retained) | 30–80ms cross-border latency; 42% more expensive storage; ¥0.50/GB egress crossing clouds |
| WeDrive | Per-seat billing (every WeCom user); no API; not designed for system-level object storage |
| OneDrive | Microsoft exit strategy; no programmatic API control |
Consequences¶
Benefits¶
- Single cloud: zero egress between COS, TDengine CVM, CI/MetaInsight, and Tencent CDN
- 42% cheaper standard storage than S3 (¥0.099 vs. ¥0.165/GB)
- 23% cheaper egress (¥0.50 vs. ¥0.65/GB)
- 72% cheaper PUT requests
- Native integration with Tencent CI (AI image/video processing), MetaInsight (semantic search), and CDN
- S3 API compatibility preserves developer workflows
Trade-Offs¶
- Migration effort: bulk transfer from S3 and OneDrive to COS
- Global access: non-China users fetch through Cloudinary (additional hop) or Tencent CDN (limited ex-China edge nodes)
- Deep archive storage is marginally more expensive than S3 Glacier Deep Archive (¥0.01 vs. ¥0.007/GB), offset by eliminated cross-cloud egress
Supersedes¶
None.
Superseded By¶
None.