The Hyperscale tier is the recommended tier for most production workloads. It offers up to 99.95% availability (when built with multiple database replicas) and is specifically designed to enable massive scale-out when required, supporting up to 100 TB in a single database.

Hyperscale also provides near-instantaneous backups and fast restores, which can be a crucial factor for solutions that demand a low Recovery Time Objective (RTO).

Latency is similar to General, at 2-10 ms. However, the I/O operations per second (IOPS) figure, which is the ability to read and write data, is between 500 and 204,800ms, whereas this figure for the General tier is between 500 and 20,000ms. These factors make the Hyperscale tier the best choice for most production workloads.

Information note

IOPS is a common measure for how fast a disk performs. Basically, the higher the IOPS, the faster the disk.

Due to the underlying architecture, both the Hyperscale and General tiers can suffer momentary outages or temporary performance issues if a primary node fails over to a standby node.

If your applications cannot stand any interruption to services or require lower latencies, then the next tier up should be considered.

Business Critical/Premium tier

The Business Critical tier (or Premium tier when using DTU-based pricing) provides the lowest latency and fastest IOPS of the available options.

Whereas the Hyperscale and General tiers use Azure Blob storage for the underlying data files, the Business Critical tier uses locally attached, high-speed SSDs. Built around SQL Always On technologies, the Business Critical tier uses a cluster of servers all connected to the same storage, enabling latencies of 1 to 2 ms and IOPS between 5,000 and 204,800ms. The clustered nature of the platform also offers even better availability, with an SLA of 99.995%.

The following diagram shows an example of the underlying architecture:

Figure 12.3 – Azure SQL Database Business Critical architecture

Azure SQL Database Business Critical is ideally suited for high-speed solutions such as analytics or applications that perform a lot of read and write operations. However, it is only available for Azure SQL Database; Azure SQL Managed Instance is not supported on this tier. Azure SQL has the most significant number of options for pricing models, types, and tiers. Azure Cosmos DB, by comparison, has fewer choices.