Object Storage Service (OSS)

Object Storage Service (OSS) is Alibaba Cloud's highly scalable, durable, and cost-effective object storage solution. OSS is the equivalent of AWS S3 or Azure Blob Storage, and is one of the most widely used Alibaba Cloud services.

---

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 48.8 TB per object)
• Metadata — information about the object (content type, custom headers, etc.)

Unlike file systems, object storage uses a flat namespace — there are no real directories, although you can use key prefixes to simulate a folder structure.

---

Buckets

A bucket is a container for objects. Key properties:

• Globally unique name — bucket names must be unique across all of Alibaba Cloud
• Region-specific — each bucket is created in a specific region
• Unlimited objects — no limit on the number of objects in a bucket
• Access control — you can set buckets as private, public-read, or public-read-write

Bucket Naming Rules

• 3 to 63 characters long
• Lowercase letters, numbers, and hyphens only
• Must start and end with a letter or number

---

Storage Classes

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

Storage Class	Use Case	Retrieval	Minimum Storage Duration
Standard	Frequently accessed data	Immediate	None
Infrequent Access (IA)	Data accessed less than once a month	Immediate	30 days
Archive	Data rarely accessed, retrieval takes minutes	1 minute to restore	60 days
Cold Archive	Long-term archival, retrieval takes hours	1–12 hours to restore	180 days
Deep Cold Archive	Compliance archival, lowest cost	12–48 hours to restore	180 days

Lifecycle Rules

Lifecycle rules automatically transition objects between storage classes or delete them after a specified period:

Day 0:   Upload to Standard
Day 30:  Transition to IA
Day 90:  Transition to Archive
Day 365: Delete

---

Data Durability and Availability

Storage Class	Durability	Availability
Standard	99.9999999999% (twelve 9s)	99.99%
IA	99.9999999999%	99%
Archive	99.9999999999%	99% (after restore)