Cloud Object Storage (COS)

Cloud Object Storage (COS) is Tencent Cloud's highly scalable, durable, and cost-effective object storage service. COS is the equivalent of AWS S3 or Alibaba Cloud OSS.

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What is Object Storage?

Object storage stores data as objects within buckets. Each object consists of:

• Key — a unique name within the bucket (e.g., images/photo.jpg)
• Data — the file content (up to 48.82 TB per object)
• Metadata — information about the object (content type, custom headers)

Object storage uses a flat namespace — key prefixes simulate a folder structure.

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Buckets

A bucket is a container for objects:

• Globally unique name — format: <BucketName-APPID> (e.g., my-bucket-1250000000)
• Region-specific — each bucket is created in a specific region
• Unlimited objects — no limit on number or total size
• Access control — private, public-read, or public-read-write

Bucket Naming Rules

• 1 to 50 characters (excluding APPID suffix)
• Lowercase letters, numbers, and hyphens
• Cannot start with a hyphen

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Storage Classes

COS offers multiple storage classes to balance cost and access patterns: