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. OBS delivers up to 99.9999999999% (12 nines) of data durability, and up to 99.995% of availability, far higher than a conventional architecture would offer.

OBS data durability and availability vary depending on the storage class and redundancy storage policy. For details, see Comparison of Storage Classes.

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 99.995% availability means that if you keep accessing OBS for 100,000 minutes (about 69 days), you can expect no more than 5 minutes of unavailability.