Choosing storage

Choose both a storage provider and a mode. The provider stores job data. The mode controls whether workers coordinate through memory or through the provider.

Mode	Where jobs are coordinated	Worker processes	Survives restart	Use for
InMemory	Current process	One	No	Unit tests, local demos, disposable work.
SingleServer	Memory backed by durable storage	Exactly one	Yes	Low-latency single-instance services.
Distributed	Storage provider	One or more	Yes	Scale-out and high availability.

A durable SQL provider uses single-server mode unless you call UseDistributed(). Redis always uses distributed mode. Do not connect two scheduler processes to the same single-server storage; the mode expects exactly one process and fails when it detects another.

Supported features

Provider	Queue	Recurring	Graph	Fair groups	Modes
In-memory	✓	✓	✓	✓	In-memory only
EF Core SQL	✓	✓	✓	✓	Single-server, distributed
LinqToDB SQL	✓	✓	✓	✓	Single-server, distributed
Redis	✓	✓	—	—	Distributed

Queue support includes scheduling, execution history and job monitoring. Recurring support stores schedules and creates runs when they are due. Graph support adds batches, dependencies, continuations and batch monitoring. The dashboard hides graph views when storage does not support them.

Tradeoffs

• In-memory is fast and predictable in tests, but a restart loses pending jobs and history.
• Single-server selects work in memory and writes every change to SQL. It restores that state after a restart but cannot fail over to another process.
• Distributed SQL coordinates workers through the database. It supports multiple processes and all job features.
• Redis offers efficient distributed queues and recurring work, but not batches, continuations or fair queues.

A custom provider

Implement IJobStorage to support queues. Add IRecurringJobStorage, IJobGraphStorage, and IFairQueueStorage only for features the provider supports.

Single-server storage needs two extra interfaces for restart recovery. IJobStorageReplica claims the exact job IDs selected by the in-memory queue. IJobGraphStorageReplica loads incoming continuation links at startup. A provider must implement both interfaces, plus recurring and graph support, to use single-server mode.

Starting or disposing the provider more than once must be safe. It must save each claim, recurring run and graph change in one operation so workers cannot create duplicates or overwrite each other. It must also enforce leases and worker ownership, and return monitoring results in pages.

Run the JobStorageConformanceSuite from Immediate.Jobs.Testing with the same service registration an application would use. Select the tests that match the provider’s features. See Testing jobs and the contract summary in API reference.