Higher log rate for business critical service tier in Azure SQL MI

We are thrilled to publish this article dedicated to a significant improvement for Azure SQL Managed Instance: customers using the business critical service tier on premium series hardware can now benefit from a much higher log rate. This update brings improved transaction processing, faster data recovery, and expanded scalability - empowering mission-critical operations in the cloud. This enhancement is available to all instances globally at no additional cost.

Enhanced Log Rate Performance

In August 2023, we announced the increase of the maximum log rate for instances operating on the Business Critical service tier with premium series hardware. The maximum log rate has been raised from 96 MiB/s to 192 MiB/s which was a huge benefit for instances running over 20 vCores. Log rate is allocated per vCore; thus, as additional vCores are provisioned, the log rate scales accordingly.

With the new enhancement from June 2025, the per-vCore log rate for the Business Critical service tier on premium series hardware has been substantially improved - from 4.5 MiB/s to 12 MiB/s – extending the log rate benefit to instances running on up to 20 vCores. This development enables significantly higher transactional throughput and accommodates more demanding workloads.

The maximum achievable log rate per instance remains capped at 192 MiB/s. Consequently, increasing the number of vCores up to 16 will scale the log rate, but beyond 16 vCores, the log rate does not increase further and remains constant regardless of additional vCore allocation.

This improvement enables greater efficiency for high-throughput, mission-critical applications and ensures that your Azure SQL Managed Instance can handle even more intensive workloads with ease.

What Is Log Rate and Why Is It Important?

The log rate (transaction log throughput) determines how efficiently your database can process transactional activity - such as inserts, updates, and deletes. A higher log rate means:

• Faster and more reliable transaction processing
• Quicker restore operations
• Enhanced support for high-throughput, business-critical applications

Understanding Azure SQL Managed Instance Service Tiers

Azure SQL Managed Instance offers two distinct service tiers to meet different needs:

• General Purpose: Designed for most business workloads, providing balanced and cost-effective compute and storage options. Currently in preview, there is a Next-gen General Purpose version, which brings significant performance improvements at the same price. Learn more at Introducing Azure SQL Managed Instance Next-gen GP
• Business Critical: Tailored for apps requiring the highest resilience, fastest failover, and enhanced performance, now with even greater log throughput on premium series hardware.

We remain committed to helping you achieve optimal performance and reliability for your most critical applications with Azure SQL Managed Instance. Stay tuned for more updates and share your feedback with us anytime!

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