Introduction
Service Level Agreements (SLAs) define the expected performance and availability of a system, particularly in disaster recovery and high-availability scenarios. Two crucial metrics in an SLA are:
Recovery Point Objective (RPO): The maximum acceptable data loss measured in time. It determines how frequently backups or replications must occur.
Recovery Time Objective (RTO): The maximum acceptable downtime before system restoration is required. It defines how quickly a system must recover after failure.
SQL Server 2019 provides multiple high-availability and disaster recovery solutions that cater to different SLA requirements. Below, we explore two different scenarios, each highlighting how SQL Server 2019 meets various RPO and RTO needs.
Scenario 3: Moderate Data Loss & Recovery in Hours (Corporate Intranet Database)
Business Requirement: A company’s internal intranet database contains documents and reports that do not change frequently. Losing a few hours of data is acceptable, and recovery within a few hours is sufficient.
SQL Server 2019 Solution:
Log Shipping: Scheduled transaction log backups shipped to a secondary server every hour.
Daily Full Backups: A full backup runs once per day with differential backups every 12 hours.
RPO: Up to 1 hour (data loss depends on the last shipped log backup).
RTO: A few hours (manual failover and restoration from backups).
This cost-effective solution ensures that the system can be restored without expensive high-availability configurations.
Scenario 4: High Data Loss & Longer Recovery (Archival Database System)
Business Requirement: A historical data warehouse used for analytics and reporting does not require frequent updates, and losing a day’s worth of data is acceptable. Recovery can take up to a full day.
SQL Server 2019 Solution:
Weekly Full Backups & Nightly Differential Backups: Since data changes infrequently, backups are scheduled with longer intervals.
Offsite Backup Storage: Backups are stored in Azure Blob Storage for disaster recovery.
RPO: Up to 24 hours (data loss depends on the last backup).
RTO: Up to 24 hours (restoration from backups and system reconfiguration).
This approach optimizes cost efficiency for less critical data while ensuring long-term retention.
Conclusion
SQL Server 2019 provides a range of high-availability and disaster recovery options to meet different RPO and RTO requirements. From mission-critical systems requiring instant failover to archival databases with relaxed recovery timelines, businesses can tailor their database strategies to meet SLA commitments effectively. The choice of approach depends on how much data loss is tolerable and how quickly a system must recover.
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