Use the set-startup-only keyword if you want to reboot the I/O module only when the fabric interconnect in its data path reboots. If you do not use the set-startup- only keyword, the I/O module reboots and disrupts traffic. In addition, if Cisco UCS Manager detects a protocol and firmware version mismatch between it and the I/O module, it updates the I/O module with the firmware version that matches its own and then activates the firmware and reboots the I/O module again. https://www.cisco.com/c/en/us/td/docs/unified_computing/ucs/ucs- manager/CLI-User- Guides/Firmware-Mgmt/4- 0/b_UCSM_CLI_Firmware_Management_Guide_4- 0/b_UCSM_CLI_Firmware_Management_Guide_4-0_chapter_011.html