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

Question 1:

Q: For selecting data redundancy policy upon bucket creation, what is the difference between single-AZ storage and multi-AZ storage?

A: Multi-AZ storage means data is stored in multiple AZs, improving data reliability. Single-AZ storage means data is stored in a single AZ, with lower costs.

Question 2:

Q: Is data stored as copies in multiple AZs when the data redundancy policy is set to multi-AZ storage? 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 data redundancy policy without deleting the bucket?

A: No. Once a bucket is created, you cannot change the data redundancy policy. You can create a bucket with the wanted data redundancy policy, and migrate data to the new bucket.