• Object Storage Service

  1. Help Center
  2. Object Storage Service
  3. User Guide
  4. Product Introduction
  5. Basic Concepts
  6. Object


An object is a basic data unit of OBS. It contains both data and the metadata that describes data attributes. Data uploaded to OBS is stored into buckets as objects. For details about a bucket, see Bucket.

An object consists of data, metadata, and a key.
  • A key specifies the name of an object. An object key is a string ranging from 1 to 1024 characters in UTF-8 format. The object key for each object in a bucket must be unique.
  • Metadata provides a description of objects. Metadata contains system metadata and user metadata. All metadata is uploaded to OBS as key-value pairs.
    • System metadata is automatically generated by OBS and is used for processing object data. System metadata includes information about Date, Content-length, Last-modify, and Content-MD5.
    • User metadata is specified by users when objects are uploaded, and user metadata is used to describe objects.
  • Data is the information contained by an object.

Generally, objects are managed as files. However, OBS is an object-based storage service and it does not involve the file and folder concepts. For easy data management, OBS provides a method to simulate virtual folders. By adding a slash (/) in an object name, for example, test/123.jpg, you can simulate test as a folder and 123.jpg as the name of a file under the test folder. However, the key remains test/123.jpg.

When uploading an object, set a storage class; otherwise, the object will use the storage class of the bucket to which the object is uploaded. You can also change the storage class of an existing object in a bucket.

In either OBS Console or OBS Browser, you can use folders directly.