Azure constantly retains several copies of data to provide high levels of data availability. Some data redundancy solutions are accessible to clients in Azure, depending on the criticality and duration necessary to provide access to the replica.
- Locally Redundant Storage (LRS): In this type, data is replicated across different racks in the same data centre. It is the cheapest redundancy option and ensures that there are at least three copies of the data.
- Zone Redundant Storage (ZRS): It ensures that data is replicated across three zones within the primary region. Azure takes care of DNS repointing automatically in case of zone failure. It might require a few changes to the network settings for any applications accessing data after the DNS repointing.
- Geo-Redundant Storage (GRS): In this type, data is replicated across two regions and ensures that data can be recovered if one entire region goes down. It may take some time for the Geo failover to complete and make data accessible in the secondary region.
- Read Access Geo Redundant Storage (RA-GRS): It is much similar to GRS but with the added option of reading access to the data in the secondary region in case of a failure in the primary region.
