Q. Why do I need to use a Geographically Redundant Storage account in Azure with Azure Site Recovery?
A. Azure has a number of different types of storage which have different levels of resiliency, for example:
- Locally Redundant Storage (LRS) - Data is replicated 3 times within a datacenter
- Zone Redundant Storage (ZRS) - 3 copies of data stored over multiple datacenters within a region
- Geographically Redundant Storage (GRS) - 3 copies of data within a datacenter and 3 copies of data in a datacenter in a paired region 100's of miles away
Azure Site Recovery (ASR) provides DR services for services that run in Azure in the event of a disaster. A key part of this protection is the replication of data from the source location into an Azure storage account. A requirement for the storage account is that is needs to be GRS. The reason for this is ASR is providing DR services and in the event of a failover to Azure its important the failover over services are still resilient to failure, i.e. and Azure problem. Therefore by using GRS storage the data for the services is replicated to the paired Azure region and available in the event of an Azure issue.