What is Tech Support Mode?
Tech Support Mode is a command-line interface for diagnosis and repair of an ESXi system. It is enabled but inactive for default installations. In ESX 4.1, Tech Support Mode can be enabled and disable through the DCUI or through vCenter Server, and can also be accessed remotely via SSH. For more information, see the ESXi Management page. To learn how Tech Support Mode works in ESXi 4.0, please refer to KB1003677.