Object Storage Service (OSS) has disaster recovery capabilities that support zone-redundant storage (ZRS) and cross-region replication (CRR) for data centers in a region or across regions.


ZRS uses the multi-zone mechanism to distribute user data across multiple zones in the same region. If one zone becomes unavailable, you can continue to access the data that is stored in other zones.

ZRS provides disaster recovery at the data center level. If a data center becomes unavailable due to network disconnections, power outages, or other disasters, OSS continues to provide highly consistent services. This way, the services are not interrupted, and data is not lost during failovers. This helps meet the strict requirements of key business systems for which the recovery time objective (RTO) and the recovery point objective (RPO) must be zero.

ZRS supports the Standard and Infrequent Access (IA) storage classes. The following table compares the two storage classes.
Data durability (designed for)99.9999999999% (twelve 9's)99.9999999999% (twelve 9's)
Service availability99.995%None
Service availability (designed for)None99.995%
Minimum billable size of objectsActual size of objects64 KB
Minimum storage periodNone30 days
Data retrieval feesNoneBased on the size of retrieved data. Unit: GB.
Data accessReal-time access with a latency of millisecondsReal-time access with a latency of milliseconds
Image Processing (IMG)SupportedSupported

For more information, see ZRS in OSS Developer Guide.


CRR enables the automatic and asynchronous (near real-time) replication of objects across buckets in different OSS regions. Operations, such as the creation, overwriting, and deletion of objects, can be synchronized from a source bucket to a destination bucket.

CRR can meet the following business requirements:
  • Compliance requirements: Although OSS stores multiple replicas of each object in physical disks, replicas must be stored at a distance from each other to comply with regulations. CRR allows you to replicate data between geographically distant data centers to comply with regulations.
  • Minimum latency: You have users who are located in two geographical locations. To minimize the latency when the users access objects, you can store replicas of objects in OSS data centers that are geographically closer to these users.
  • Data backup and disaster recovery: You have high requirements for data security and availability, and want to explicitly maintain replicas of all written data in a second data center. If one OSS data center is damaged in a disaster, such as an earthquake or a tsunami, you can use backup data from the other data center.
  • Data replication: To ensure the availability of your business, you may need to migrate data across different data centers.
  • Operational reasons: You have compute clusters deployed in two different data centers that need to analyze the same group of objects. You can store object replicas in the two regions.

CRR can meet your requirements for cross-region disaster recovery and data replication. Objects in the destination bucket are exact replicas of those in the source bucket. They have the same object names, versioning information, object content, and object metadata, such as the creation time, owner, user metadata, and object access control lists (ACLs). CRR can replicate objects that are not encrypted and objects that are encrypted by using SSE-KMS or SSE-OSS at the server side.

For more information, see CRR in OSS Developer Guide.