Azure SQL Database service tiers: General Purpose vs Business Critical vs Hyperscale vs Serverless
Verdict: Business Critical gives 1-2 ms latency and a free readable replica. Hyperscale scales storage to 128 TB independently of compute. Serverless auto-pauses for intermittent workloads. General Purpose is the balanced default.
| Criterion | General Purpose | Business Critical | Hyperscale | Serverless |
|---|---|---|---|---|
| Architecture | Remote Blob storage, higher latency | Local SSD, 1-2 ms latency, free read-only replica | Storage scales independently of compute, read scale-out | Autoscaling compute within a min/max vCore range |
| Max storage | 4 TB | 4 TB | 128 TB | 4 TB (General Purpose based) |
| Choose when | Balanced default workload | Low-latency OLTP needing a free reporting replica | Database grows beyond 4 TB or needs fast storage scaling | Intermittent dev/test workloads that should auto-pause |
Rules
- Business Critical uses local SSD storage for 1-2 ms latency and includes a free built-in read-only replica with fast failover.
- Hyperscale is the recommended default for new OLTP and HTAP workloads: storage grows to 128 TB and scales independently of compute.
- The Serverless compute tier autoscales within a configured vCore range and auto-pauses during inactivity, resuming on the next connection.
- Serverless requires no manual or programmatic scaling action; the service scales compute automatically on workload demand.
- Reverse migration out of Hyperscale to General Purpose is permitted only within 45 days of the original migration to Hyperscale.
- General Purpose and Business Critical both cap a single database at 4 TB, so a larger database needs Hyperscale.
Traps
- After the 45-day reverse-migration window closes, a Hyperscale database cannot reach Business Critical via the documented path; treat Hyperscale as effectively permanent.
- Business Critical is a service tier, not the autoscaling compute tier; auto-pause and autoscale are Serverless capabilities.