The command to check I/O health and validate connectivity after a controller upgrade is purehost monitor --balance.

Following an upgrade (especially after a controller reboot or failover/giveback), it is essential to verify that the host Multipath I/O (MPIO) drivers have re-established connectivity to all paths.

purehost monitor: Displays real-time performance statistics (IOPS, Bandwidth, Latency) for connected hosts.

--balance: This specific flag breaks down the metrics per initiator (HBA port) for each host.

Why it's used: An Implementation Engineer uses this to look for 'imbalanced' flow. If one initiator shows high IOPS and another shows zero, it indicates a dead path, a zoning issue, or an MPIO driver that failed to recover the path to the upgraded controller. Options A and B provide static configuration lists (mappings and WWNs) but do not show live I/O flow, making them insufficient for health monitoring.

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