Minimal Configuration & Single User Modes

In the event of a server failure, you might need to start SQL Server in either the Minimal Configuration or Single User Mode.

They both

• Only allow 1 user to connect
• Disable the CHECKPOINT process

Minimal Configuration Mode also prevents startup procedures from being run however.

Links:

Starting SQL Server in Single-User Mode (Startup option -m)
Starting SQL Server with Minimal Configuration (Startup option -f)