Can we Split the Virtual Chassis OS6900 Switch and perform standalone software upgrade to achieved minimal network interruption to the connected device on the VC Switch? Is it doable? Can we encounter issue when we restore the VC links once both Switches were upgraded successfully? TIA!
Yes you can split and reassemble an OS6900 stack but this does not minimize downtime. I would recommend to perform an ISSU instead. This option has the least amount of downtime. Please check the release notes of the target firmware release for upgrade instructions.
In a VC of 2, one unit acts as master and the other as slave. When you split the stack, both units become master. You need at least one reboot per chassis to perform an upgrade. Once two units that are powered up, are reconnected, a re-election takes place, depending on the configured settings and/or device uptime or chassis mac which might result in the slave unit rebooting to assume the new role in the VC. Hence my suggestion to use In Service Software Upgrade which is designed to minimize downtime.
During ISSU, one chassis remains up at all times and keeps forwarding traffic, thus minimizing downtime.