Skip to main content

Redundancy Options

Updated Nov 16, 2020 ·
NOTES

This is not an exhaustive documentation of all the existing Azure Services. These are summarized notes for the Azure Certifications.

To see the complete documentation, please go to: Azure documentation

Redundancy Options​

Azure Storage provides six redundancy options, ranging from locally-redundant to read-access geo-zone-redundant storage. Each option offers different levels of redundancy and pricing.

Note that not all of these options are available in every region or for every type of data.

Locally-Redundant Storage (LRS)​

  • Replication: Across racks in the same data center.

  • Disaster Consideration: Data could be lost in a data center disaster.

  • Recommendation: Use only if data reconstruction is easily achievable.

Zone-Redundant Storage (ZRS)​

  • Replication: Across three zones within one region.

  • Disaster Consideration: Ensures data availability even if an entire zone goes down.

Geo-Redundant Storage (GRS)​

  • Replication: Across two regions.

  • Disaster Consideration: Requires geo-failover in the event of a regional disaster to access data in the secondary region.

Read-Access Geo-Redundant Storage (RA-GRS)​

  • Replication: Same as GRS.

  • Additional Feature: Allows reading data immediately from the secondary region in case of a disaster in the primary region.

  • Write Access: Not available until Microsoft restores availability in the primary region.

Geo-Zone-Redundant Storage (GZRS)​

  • Replication: Across three availability zones in the primary region.

  • Difference from GRS: Combines zone-redundant storage and geo-redundant storage.

Read-Access Geo-Zone-Redundant Storage (RA-GZRS)​

  • Replication: Same as GZRS.

  • Additional Feature: Allows immediate reading from the secondary region in case of a disaster in the primary region.

  • Write Access: Not available until Microsoft restores availability in the primary region.

Redundancy Pricing​

Naturally, each of these redundancy options has a different price.

  • Locally-redundant storage being the cheapest and
  • Read-access geo-zone-redundant storage being the most expensive.
  • RA-GRS is actually more expensive than GZRS even though it’s less redundant because it provides instant access to your data in the secondary region.