SQL Server 2012 offers flexible HADR solutions to ensure data availability and minimize downtime. With features like AlwaysOn, failover clustering, and log shipping, it helps safeguard workloads across maintenance events and unexpected failures.
AlwaysOn Availability Groups:
An availability group is a set of user databases that fail over together from one SQL Server instance to another within the same Windows Server Failover Clustering (WSFC) cluster.
Azure SQL Managed Instance link:
It enables near real-time data replication from on-premises SQL Server to Azure SQL Managed Instance. It ensures hybrid connectivity with minimal downtime and supports seamless cloud migration or analytics.
AlwaysOn Failover Cluster Instance (FCI) :
An FCI is a single logical SQL Server instance installed across nodes in a WSFC cluster, but only active on one node at a time.
Database Mirroring – High-safety (Sync + Witness):
Maintains two database copies on separate SQL Server instances. Automatic failover requires a third instance, called a witness, which doesn’t serve the database but monitors the partners.
Database Mirroring – High-performance (Async):
Log records are sent from the principal to the mirror server without waiting for acknowledgment, minimizing delay and boosting performance.
Log Shipping:
Recorded transaction logs are automatically copied and applied to a standby database on another server for disaster recovery.