In Microsoft Azure Storage, maintaining high availability and durability of data is achieved through replication. There are multiple redundancy options - LRS (Locally Redundant Storage), ZRS (Zone- Redundant Storage), GRS (Geo-Redundant Storage), and RA-GRS (Read-Access Geo-Redundant Storage) - each serving different scenarios.
However, when the requirement is to create a secondary copy of blob data in a specific region (for example, when blob data is added in North Europe, a copy must be created in East US), geo-redundant storage (GRS) cannot be used directly because GRS replicates data automatically to a paired region, not to a region of your choice. In this case, North Europe's paired region is West Europe, not East US. Therefore, GRS does not meet the goal.
The Microsoft Azure Administrator documentation specifies that the correct method for replicating data between user-defined regions is Object Replication for Block Blobs (OR).
Object replication allows you to:
* Automatically replicate new and updated block blobs between two storage accounts in different Azure regions.
* Use replication policies to define source and destination containers.
* Minimize administrative effort, as once configured, replication occurs automatically and asynchronously.
* Retain independent storage accounts, ensuring flexibility and control over access and lifecycle management.
Unlike lifecycle management rules (which only move or delete blobs within the same storage account) or operational backup (which protects data for restore purposes, not replication), object replication precisely meets the requirement of maintaining a secondary copy in another chosen region.
Therefore, per Azure's official Storage replication and Object replication documentation, the correct configuration is Object replication between storage1 (North Europe) and another storage account in East US.