Introduction
High Availability is a critical component of SQL Server, ensuring minimal downtime and maintaining data integrity in case of failures.
It involves redundancy, failover mechanisms, and robust monitoring to gracefully handle issues.
Key Concepts
- Redundancy: Multiple instances of SQL Server to distribute workload.
- Failover: Automatic switching to a backup instance when the primary fails.
- Monitoring: Real-time data collection and analysis to detect issues.
- Automatic Restart: Quickly recovering from failures without manual intervention.
Components
- SQL Server Agent: Responsible for automated tasks and failover.
- Failover Cluster Instances (FCI): Multiple SQL Server instances that automatically switch to each other in case of failure.
- Virtual Standby (VS): A snapshot of the SQL Server environment that can be used for failover.
- Database Mirroring: Creates redundant copies of your databases for failover.
Practical Examples
This section demonstrates how High Availability enhances operational reliability.
We'll cover scenarios of database failover and automatic restart.