What Are the Differences Between Single-AZ and Multi-AZ Storage in OBS?

Question 1:

Q: What are the differences when multi-AZ storage is enabled or disabled during the bucket creation?

A: When the multi-AZ mode is enabled, data is redundantly stored in multiple AZs, improving data reliability. Data is stored in a single AZ if the multi-AZ mode is disabled, with lower costs. For details, see Product Pricing Details.

Question 2:

Q: Is data stored as copies in multiple AZs after the multi-AZ mode is enabled? If an AZ is faulty, is data complete in other AZs?

A: The Erasure Code (EC) algorithm, instead of multiple copies, is used to ensure data redundancy in the multi-AZ mode. If the multi-AZ storage is enabled for a bucket, data is stored in multiple AZs in the same region. If an AZ is unavailable, data can still be properly accessed in other AZs. The multi-AZ mode is suitable for data storage scenarios that require high reliability. The multi-AZ storage tolerates only faults of a single AZ.

Question 3:

Q: Can I change the status of the multi-AZ mode without deleting the bucket?

A: No. If the multi-AZ mode is enabled upon creation of a bucket, it cannot be disabled. You can migrate data to another bucket and delete the bucket that has the multi-AZ mode enabled, if you do not need multi-AZ storage.