Using the option “coldboot” in your firmware upgrade tells the VDX to automatically reload once the firmware is downloaded and ready for installation. This option is clearly outlined in the Network OS Software Upgrade Guide.
The coldboot option in the firmware download command allows you to download new firmware onto a switch and forces the switch to perform a cold reboot.
I believe the option that you are looking for is the “noreboot” option. This command is also detailed in the Upgrade Guide under “Downloading firmware using the manual option” .
On a Top-of-Rack (ToR) switch, this manual option allows you to specify the noreboot and nocommit options so that you have exact
control over the firmware download sequence.
3. If you entered the noreboot option, enter the reload command to reboot the switch. If you entered y after the prompt, the switch will reboot automatically. The switch performs a reboot and comes up with the new firmware. Your current CLI session will automatically disconnect.
I would also recommend reviewing the following article for NOS upgrade Best Practices:
NOS Firmware Upgrade Best Practices
I hope this helps answer your question and makes future upgrade go more smoothly.
Principal Technical Support Engineer / Extreme Networks