How Are the Durability and Availability of OBS?

OBS provides multi-level reliability assurance for storage media, servers, cabinets, data centers, and regions by leveraging the following technologies: slow disk or bad sector detection, intra-AZ device and data redundancy, cross-AZ data disaster recovery, cross-region replication, and more. It offers up to 99.9999999999% (12 nines) of durability and up to 99.95% of availability for multi-AZ storage, much higher than those of the conventional architecture.

The 12 nines of durability means that the average annual loss rate of objects is expected to be 0.0000000001%. For example, if you store 100 million objects in OBS, only one object may be lost every 10,000 years.

Availability is the service continuity. A 99.95% availability means that if you keep accessing OBS for 10,000 minutes (about 7 days), you can expect no more than 5 minutes of unavailability.