About Logical Devices
A logical device lets you run one application instance .
When you add a logical device, you also define the application instance type and version, assign interfaces, and configure bootstrap settings that are pushed to the application configuration.
Standalone and Clustered Logical Devices
You can add the following logical device types:
Standalone—A standalone logical device operates as a standalone unit or as a unit in a High Availability pair.
Cluster—A clustered logical device lets you group multiple units together, providing all the convenience of a single device (management, integration into a network) while achieving the increased throughput and redundancy of multiple devices. Multiple module devices, like the Firepower 9300, support intra-chassis clustering. For the Firepower 9300, all three modules must participate in the cluster.