Data Redunancy for Azure Storage

This blog covers the various options available for data redundancy in Azure.

AZURE DATA REDUNDANCY

Data in Azure is replicated 3 times in a single site at the lowest cost level, the options are:

• Locally-Redundant Storage (LRS)
• Zone-Redundant Storage (ZRS)
• Geo-Redundant Storage (GRS)
• Geo-Zone-Redundant Storage (GZRS)

LRS - LOCALLY-REDUNDANT STORAGE

LRS will replicate your data 3 times across a single datacenter in your primary region. This is the lowest cost option as it provides basic redundnacy, protecting against failign drives or server racks but if something affected the whole datacenter then all copies of the data are affected.

 

 

ZRS - ZONE REDUNDANT STORAGE

Zone Redundancy takes it a step further by replicating your data across 3 availabilty zones in your primary region. Each of these availability zones are separate physical buildings with their own power, cooling and networking.

This protects you by allowing data to be accessed if a datacenter goes down as you will have two others for accessing your data. ZRS supports read / write operations which happens synchronously to all copies when writing to a file. If one zone does go down then Azure will handle re-pointing DNS to keep the data accessible.

 

 

GRS - GEO-REDUNDANT STORAGE

When you create a storage account, you select its primary region. Azure Regions have pairs, your primary region will have a distant pair which can be used for redundancy.

GRS is LRS but over two regions. In your primary region, your data is copied 3 times within a single physical site. The sam data is then copied to the paired region where it is copied 3 times again in a single physical site.

 

 

GZRS - GEO-ZONE-REDUNDANT STORAGE

This takes the ZRS concepts but adds a second LRS backup in the paired region. It behaves like ZRS coping the data over 3 availability zones in your primary region but then uses LRS in your paired region to have 3 copies of your data within a single physical site in the secondary region.