Storage Classes

Application Scenario

OBS provides three storage classes: Standard, Infrequent Access, and Archive. For more information about billing for different storage classes, see Storage Space.

Comparison of Storage Classes

a: Minimum measurement unit refers to the lower size limit for object billing. For example, if you upload a Standard object of 32 KB (smaller than the minimum measurement unit of 64 KB), you will be billed for a 64 KB object.

b: Minimum storage duration refers to the lower storage limit for object billing. For example, if an Infrequent Access object has been stored in OBS for 20 days (shorter than the minimum storage duration of 30 days) and then deleted, you will be billed for 30 days.

Bucket Storage Classes and Object Storage Classes

You can specify the storage class for a bucket when creating the bucket. You can also change the storage class of a bucket after the bucket is created.

An object inherits the storage class of the bucket where it is uploaded. You can specify a storage class for an object when uploading it, or you can change the object storage class after the object is uploaded.

Changing the storage class of a bucket does not change the storage classes of existing objects in the bucket, but newly uploaded objects inherit the new storage class by default.

By default, objects in Archive storage class must be restored to Standard storage class before they can be downloaded. You can enable Direct Reading to directly download objects in Archive storage class without restoring them first. Direct Reading will be charged.

Changing Bucket Storage Classes

The storage class of a bucket can only be manually changed.

Figure 1 shows the bucket storage class transition rules. OBS Standard and Infrequent Access storage classes support both single-AZ and multi-AZ redundancy policies, while the Archive storage class supports only the single-AZ redundancy. The data redundancy policy of a bucket cannot be modified, even when its storage class is changed.

Figure 1 Bucket storage class transition rules

Notes:

• Changing the storage class of a bucket does not change the storage classes of existing objects in the bucket. The storage class of an object uploaded later will inherit the new storage class of the bucket by default. You can also configure lifecycle rules to change storage classes of objects in a batch.

  For example, if bucket1 is in the Standard storage class and contains object1, when bucket1's storage class is transitioned to Infrequent Access, object1 is still in the Standard storage class. If you upload object2 to bucket1 after the transition, object2 will be in the Infrequent Access storage class.

• After a bucket is changed from Archive to Standard or Infrequent Access, Archive objects in the bucket are not automatically restored.

Changing Object Storage Classes

The storage class of an object can be changed manually or automatically. Figure 2 shows the object storage class transition rules.

• Manual transition: After an object is uploaded, you can manually change its storage class.

  Objects can be manually changed from Standard to the Infrequent Access or Archive storage class, or from Infrequent Access to Standard or Archive. Objects in the Archive storage class must be restored before they can be manually changed to the Standard or Infrequent Access storage class. Transitioning objects in the Infrequent Access or Archive storage class involves retrieval fees, so you are advised to perform transitions based on the object access frequency and scenario.

• Automatic transition: OBS provides lifecycle rules for you to automatically transition objects from one storage class to another. For details, see Lifecycle Management.

  Objects can be automatically transitioned from Standard to the Infrequent Access or Archive storage class, or from Infrequent Access to Archive.

Figure 2 Object storage class transition rules

Notes:

• After objects in the Standard storage class are transitioned to Infrequent Access or Archive storage class, their restoration status is Unrestored.
• The minimum storage duration is 30 days for Infrequent Access storage, and 90 days for Archive storage. If an object is transitioned to another storage class before it has been stored for the required minimum storage duration, you need to pay for a full 30 or 90 days.

How to Use

You can use OBS Console, APIs, SDKs, OBS Browser+, or obsutil to configure storage classes for buckets and objects.