Azure SQL Database: High Availability and Disaster Recovery Samples

Introduction

This repository provides a collection of code samples and best practices to help you implement effective High Availability (HA) and Disaster Recovery (DR) solutions for your Azure SQL Database. Ensuring your data is accessible and protected against various failure scenarios is critical for business continuity.

We cover various aspects of HA/DR, including:

• Active Geo-Replication for read-scale and DR.
• Auto-failover groups for seamless application failover.
• Point-in-time restore (PITR) and long-term backup retention.
• Implementing HA/DR with Always On Availability Groups (for SQL Server on Azure VM, though concepts are related).
• Strategies for application resilience during failover events.

Key Concepts & Features

High Availability (HA)

Azure SQL Database is designed with built-in high availability. It utilizes technologies like database mirroring and Always On Availability Groups to ensure that your database is always accessible, even in the event of hardware failures or datacenter outages. For a single database, Azure SQL Database provides at least 99.99% availability.

Disaster Recovery (DR)

Disaster Recovery focuses on protecting your data from larger-scale outages, such as regional disasters. Azure SQL Database offers several DR capabilities:

• Active Geo-Replication: Asynchronously replicates your database to another Azure region. This allows for quick manual failover to a secondary replica in case of a disaster.
• Auto-failover groups: Simplify disaster recovery by enabling automatic or manual failover of a group of databases to another region. These groups manage the failover process and provide a readable secondary replica.
• Backup and Restore: Azure SQL Database automatically backs up your databases and allows you to restore them to any point in time within the retention period. Long-term backup retention can be configured for extended archival needs.

Sample Scenarios & Code

Below are links to specific code samples and walkthroughs:

1. Setting up Active Geo-Replication

Learn how to configure and manage active geo-replication for your Azure SQL Database.

• PowerShell Script for Geo-Replication Setup
• Azure CLI Commands for Geo-Replication
• REST API Example

2. Implementing Auto-Failover Groups

Discover how to use auto-failover groups to simplify application failover.

• ARM Template for Auto-Failover Group Deployment
• Application Code Considerations for Failover

3. Backup and Restore Strategies

Explore how to leverage Azure SQL Database's backup capabilities.

• Automating Point-in-Time Restore
• Configuring Long-Term Backup Retention

4. Application Resilience

Learn how to design your applications to be resilient to database failovers.

• Handling Connection Strings During Failover
• Implementing Robust Retry Logic

Getting Started

To get started, fork this repository and begin exploring the samples. We recommend familiarizing yourself with the core concepts of Azure SQL Database HA/DR before diving into the code.

For detailed documentation, please refer to the official Azure SQL Database Business Continuity documentation.