ZRS is an additional redundancy option for Azure Storage. It provides excellent performance and extremely low latency as it stores 3 replicas of your data across 2 to 3 facilities and is designed to keep all 3 replicas within a single region, but may span across two regions.
Zone Redundant Storage (ZRS) synchronously replicates your data across three (3) storage clusters in a single region. Each storage cluster is physically separated from the others and resides in its own availability zone (AZ). Each availability zone, and the ZRS cluster within it, is autonomous, with separate utilities and networking capabilities.
When you store your data in a ZRS account it allows you to access and manage your data in the event that a zone becomes unavailable. . ZRS is best when you require strong consistency, strong durability, and high availability even if an outage or natural disaster renders a zonal data center unavailable.