Data Redundancy Capabilities of Azure Storage

Azure storage, including blob storage, provides several options for redundancy and high availability of data across data-center hardware, availability zones, and geographies. Basic redundancy is included in all Azure storage offerings, but redundancy across Azure availability zones or geographic regions will incur additional costs depending on the storage service.

Locally redundant storage (LRS) replicates data three times in a single data center in the selected region. LRS can protect against drive failure or failure of a storage rack, but it does not protect against Azure data-center failure. LRS is included in all Azure storage offerings.

Geo-redundant storage (GRS) enhances LRS by copying LRS-protected data asynchronously to a single physical location in a secondary region, where it is also duplicated synchronously three times using LRS. This can protect data from the failure of an entire Azure region. Read-access GRS (RA-GRS) enables read access from the secondary location, which can be used to establish high-availability failover in case the primary region becomes unavailable.