AZ-305 Designing Microsoft Azure Infrastructure Solutions Exam

Recommend a High Availability Solution for Relational Data

Evaluate Azure-native Replication and Failover Techniques

When designing high-availability solutions for relational data in Azure, it's essential to consider the various replication and failover techniques provided by Azure-native services. These techniques ensure continuous data processing with minimal downtime, aligning with service-level objectives for high availability and disaster recovery.

Active Geo-replication

Active geo-replication for Azure SQL Database enables you to create up to four readable secondary databases in different regions. This feature uses asynchronous replication to copy committed transactions from the primary database to secondary databases. Key benefits include:

• Disaster Recovery: Ensures minimal data loss with a typical RPO of 5 seconds.
• Load Balancing: Distributes read-only workloads across multiple geographic locations.

Auto-failover Groups

Auto-failover groups provide a group-level failover mechanism for managing failover across databases. These groups support high availability and automatic failover for multiple databases within a SQL Managed Instance or SQL Database. Advantages include:

• Automated Failover: Minimizes downtime with automatic failover across paired regions.
• Consistent Endpoints: Maintains the same connection endpoints, easing application management during failovers.

Managed Instance Availability Groups

Managed Instance availability groups resemble on-premises availability groups, offering high availability within a region and disaster recovery across regions. Main features include:

• Synchronous Replication: Ensures zero data loss with an RPO of 0 when using synchronous commit mode within a region.
• Automatic and Manual Failover: Supports both automatic failover for high availability scenarios and manual failover for disaster recovery.

Backup Solutions

Reliable backup solutions are critical for ensuring business continuity. Azure SQL Database provides built-in automated backups that support various recovery scenarios:

• Point-in-Time Restore: Enables restoring the database to any point within the retention period.
• Geo-restore: Uses geo-redundant backups to restore databases in any region, typically providing an RPO of 1 hour.
• Long-term Backup Retention: Stores backups for up to 10 years, facilitating compliance and regulatory requirements.

RTO and RPO Considerations

When designing for high availability and disaster recovery, understanding Recovery Time Objective (RTO) and Recovery Point Objective (RPO) is crucial:

• RTO (Downtime): The time required to restore full functionality after an outage.
• RPO (Data Loss): The permissible amount of data loss measured in time.

The table below compares the RTO and RPO for different Azure continuity options:

• High Availability with Zone Redundancy: RTO typically less than 30 seconds; RPO of 0.
• Disaster Recovery using Failover Groups: RTO around 60 seconds; RPO varies based on replication delay.

Conclusion

In summary, Azure-native replication and failover techniques provide robust options for achieving high availability and disaster recovery for relational data. Utilizing active geo-replication, auto-failover groups, and managed instance availability groups ensures continuous data operations with minimal downtime and data loss. Understanding and leveraging these techniques alongside your RTO and RPO requirements can significantly enhance your business continuity strategies in Azure.