Dell Force10 S4820T Installing the S4820T System - Page 36

www.dell.com | support.dell.com Figure 4-10. Three S4820Ts Connected in a Ring 52 60 Chassis 3 48 56 Chassis 2 52 60 48 56 Chassis 1 52 60 48 56 Hot-Swapping Units in a Stack You can add, remove, or swap S4820T units in an existing stack. The units in the stack and the new units can be already powered up or powered down. All units in a stack must run the same version of the operating system. If you attempt to attach a unit with a different version of the operating system to an existing stack, the CLI displays an error and the unit is not added until you install compatible software. The order in which the units come on-line or are added to or removed from the stack affects how the stack identifies them and how the units identify themselves. This influences unit numbers, management addresses, and other elements of the configuration file. Unit identification within the stack is determined by the identification algorithm you select. The default algorithm has the units self-identify as Unit 0 through Unit last based on the order in which they come on-line. So, when setting up a new set of switches in a stack, you should have no trouble forcing the identification of the management unit and unit IDs by methodically supplying power to the units in your preferred sequence. Similarly, when you add a new unit to the stack, the unit is gracefully added as Unit last (the lowest unused number) with the current configuration. Attaching a new unit may cause each unit in the stack to reload. The subsequent configuration file in each unit includes the awareness of the new unit. If you have a pre-configured unit that you want to add to the stack, but you want to make sure that the configuration does not override the configuration of the stack, add the unit while it is powered down to avoid stack management conflicts. 36 | Installing the S4820T