During an intra-series upgrade from //XR3 to //XR4, which command should the Implementation Engineer run to verify host connectivity before removing the secondary controller?
In a Non-Disruptive Upgrade (NDU), ensuring that the host is correctly multipathed and balancing I/O across all paths is critical before taking a controller down. If a host is only using paths to the controller about to be rebooted (CT0, for example), taking that controller offline would cause an outage.
The command iobalance --sampletime 30 (or its wrapper purehost monitor --balance) is the standard tool used during the upgrade procedure to validate this state.
iobalance : This script samples the I/O throughput on all ports for a specified duration (e.g., 30 seconds).
It analyzes the distribution of I/O. If it detects that I/O is heavily skewed or missing entirely on the "secondary" paths (the ones that will survive the reboot), it flags a warning.
This allows the Implementation Engineer to pause and remediate the host multipathing configuration (e.g., fixing a bad cable or zoning issue) before proceeding with the controller removal, ensuring the NDU remains truly non-disruptive.
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