Introducing "Backups on Secondary" for SQL Server Always On Availability Groups with SQL Server 2025

We’re excited to announce a major enhancement for SQL Server Always On Availability Groups Backups on Secondary, in SQL Server 2025.  

Until SQL Server 2022, you could only perform COPY_ONLY full backups and transaction log backups on a secondary replica of an Always On Availability Group. 

This enhancement in SQL Server 2025 allows you to offload all types of backups—full, differential, and transaction logs - to a secondary replica, significantly improving performance, resource utilization, and operational flexibility. 

What Is "Backups on Secondary"? 

Traditionally, backups in an Always On Availability Group were typically performed on the primary replica, which could lead to resource contention and performance degradation for mission-critical workloads. With this update in SQL Server 2025 to the Backups on Secondary feature, you can now configure your environment to perform all backup operations on a designated secondary replica. 

This includes: 

• Full backups 

• Differential backups 

• Transaction log backups 

Key Benefits 

🔄 Reduced Load on Primary Replica 

By offloading backup operations to a secondary replica, you free up CPU, memory, and I/O resources on the primary replica, ensuring that your production workloads run more smoothly and efficiently. 

🧩 Flexible Backup Strategies 

You can now design more flexible and resilient backup strategies by leveraging secondary replicas in different geographic locations or data centers. 

🛡️ Enhanced High Availability and Disaster Recovery 

In the event of a failover, backup operations can continue seamlessly on another secondary replica, ensuring continuous data protection. 

How It Works 

The feature is easy to configure using T-SQL or SQL Server Management Studio (SSMS). There are two steps to make backups run on secondary:

1. Configure backups to run on secondary replica via the AUTOMATED_BACKUP_PREFERENCE and BACKUP_PRIORITY parameters – refer to Configure backups on secondary replicas of an Always On availability group for prerequisites and detailed steps. 
2. Run the T-SQL BACKUP command using one of the tools such as SSMS or SQL Agent jobs or Maintenance plans. 

These are the same steps that have been currently in place for SQL Server 2022 and for prior versions. In the prior versions this configuration only allowed COPY_ONLY and transaction log backups. Now, starting with SQL Server 2025, with the same configuration in place, you can perform FULL, DIFFERENTIAL and T-LOG backups on a secondary replica and truly offload the backup overhead on to the secondary replica. 

You can also query system views like sys.dm_hadr_backup_is_preferred_replica to programmatically determine the preferred replica for backups. 

Final Thoughts 

The Backups on Secondary feature is a game-changer for organizations looking to optimize their SQL Server environments for performance, availability, and cost. Whether you're managing a large-scale enterprise deployment or a hybrid cloud setup, this feature gives you the flexibility and control you need to build a more efficient and resilient data platform. 

This feature is available in SQL Server 2025 CTP 2.0. You can download it and try it out today.