Overview

Background Information

An AZ is a physical location with independent power supplies and network in a region. A region contains one or more AZs that are physically isolated but interconnected through internal networks. Because AZs are isolated from each other, any fault that occurs in one AZ will not affect other AZs.

When two-AZ DR is disabled for a bucket, data is stored only in one single AZ at a lower cost. When two-AZ DR is enabled for a bucket, data is stored in two AZs to achieve higher reliability.

Buckets with two-AZ DR enabled are called fusion buckets.

Application Scenario

Two-AZ DR allows you to synchronize data to another AZ for remote backups. It is ideal for scenarios that demand high reliability.

With two-AZ DR, you can store data in two different AZs in the same region. If one AZ becomes unavailable, data can still be properly accessed from the other AZ. This ensures data reliability in case of ventilation, fire-extinguish, moisture-proof, and electricity failures.

Objects synchronized to the destination bucket in the other AZ are precise copies of those in the source bucket. Objects in both buckets have the same name and metadata (including the content, size, last modification time, creator, version ID, custom metadata, and ACL).

Contents Synchronized

When two-AZ DR is enabled, OBS will synchronize the following contents to the other AZ:

• Newly uploaded objects
• Updated objects (for example, the object content is updated)
• Deleted objects. The object copies in the other AZ will also be deleted.

Constraints

• Once configured, a two-AZ DR policy cannot be modified, so carefully plan the two-AZ DR policy in advance.

• A two-AZ DR policy may not take effect immediately upon its configuration. Accordingly, the objects that this policy is applied to may not be synchronized immediately after the policy is configured.
• Only buckets whose version is 3.0 or later support two-AZ DR. The bucket version can be viewed in the Basic Information area of the bucket's Overview page on OBS Console.

• A bucket configured with two-AZ DR does not support cross-region replication, and vice versa.
• Two-AZ DR is not available for append upload.
• After a fusion bucket is deleted, its name can be used for another bucket only 12 hours later.
• When the active cluster becomes faulty, buckets cannot be queried, created, or deleted.