Redundancy options
Azure Storage is available at several regions around the world, allowing data to be replicated within the same region or to different regions, depending on your selection. The following are the replication strategies to choose from when creating a storage account:
- Locally redundant storage (LRS) stores three synchronous copies of the data in a single facility in the same region.
- Zone-redundant storage (ZRS) is where data is stored and replicated across multiple facilities, either within one or two nearby regions.
Note
ZRS is only available only for block blobs storage. Also, once you have created a storage account with ZRS, you cannot later change it. Further information can be found at https://azure.microsoft.com/en-us/documentation/articles/storage-redundancy/.
- Geo-redundant storage (GRS) maintains six asynchronous copies of the data. Data is replicated the same way as for ZRS, but is then asynchronously replicated to a secondary far region that falls under a separate fault domain, without allowing direct access to it.
- Read-access geo-redundant storage (RA-GRS) provides all of the benefits of geo-redundant storage noted above, but it allows read access to data at the secondary region whenever the primary region becomes unavailable.
Note
A fault domain is a collection of servers and network components that share a single point of failure. To improve service availability, Azure hosts data on multiple fault domains.
