Manage orchestration data using storage providers

Durable Functions support various backend storage providers. You can configure your apps to use the two types of storage providers available to Durable Task:

• Azure managed:
  • Durable Task Scheduler (recommended)
• "Bring your own" (BYO) storage:
  • Azure Storage
  • Netherite
  • Microsoft SQL Server (MSSQL)

The Durable Task SDKs support the Azure managed Durable Task Scheduler as a storage provider.

Azure Storage

Azure Storage is one of the "bring your own" storage providers for Durable Functions. It uses queues, tables, and blobs to persist orchestration and entity state, and blob leases to manage partitions. The Azure Storage provider is built into the Durable Functions extension and doesn't have any other dependencies.

The key benefits of the Azure Storage provider include:

• No setup required - you can use the storage account that was created for you by the function app setup experience.
• Lowest-cost serverless billing model - Azure Storage has a consumption-based pricing model based entirely on usage (more information).
• Best tooling support - Azure Storage offers cross-platform local emulation and integrates with Visual Studio, Visual Studio Code, and the Azure Functions Core Tools.
• Most mature - Azure Storage was the original and most battle-tested storage backend for Durable Functions.
• Support for using identity instead of secrets for connecting to the storage provider.

The Azure Storage provider doesn't require any explicit configuration, NuGet package references, or extension bundle references. For detailed configuration options, including connections, identity-based authentication, and host.json settings, see Azure Storage provider for Durable Functions.

Microsoft SQL Server (MSSQL)

The MSSQL storage provider persists all state into an MSSQL database. It's compatible with both on-premises and cloud-hosted deployments of SQL Server, including Azure SQL Database.

The key benefits of the MSSQL storage provider include:

• Disconnected environments are supported; no Azure connectivity is required when using a SQL Server installation.
• Portable across multiple environments and clouds, including Azure-hosted and on-premises.
• Strong data consistency, enabling backup/restore and failover without data loss.
• Native support for custom data encryption (a feature of SQL Server).
• Integrates with existing database applications via built-in stored procedures.

Learn more about the MSSQL storage provider:

• The MSSQL provider documentation.
• The source code for the MSSQL storage provider.

Netherite

The Netherite storage backend was designed and developed by Microsoft Research. It uses Azure Event Hubs and the FASTER database technology on top of Azure Page Blobs.

The key benefits of the Netherite storage provider include:

• Higher throughput at lower cost compared to other storage providers.
• Supports price-performance optimization, allowing you to scale-up performance as-needed.
• Supports up to 32 data partitions with Event Hubs Basic and Standard SKUs.
• More cost-effective than other providers for high-throughput workloads.

Learn more about the Netherite storage provider:

• The Netherite documentation.
• The source code for the Netherite storage provider.
• A more in-depth evaluation of the Netherite storage provider: Serverless Workflows with Durable Functions and Netherite.

Comparing storage providers

You can use the following table to understand the significant tradeoffs between the various supported storage providers and decide which storage provider is best for your needs.