A large number of intermittent SCSI errors are suddenly appearing in a host's log, but the storage array has been verified as fully operational. The link lights on the SAN switch connections have been

Switch zone errors typically result in complete access denial or incorrect mapping, rather than intermittent data transfer errors on an established path.

Intermittent SCSI errors, even with active link lights, often indicate underlying data integrity issues on the Fibre Channel link, such as CRC errors, discarded frames, or retransmissions. Port error counters provide specific metrics on these types of issues, helping to pinpoint the exact nature of the problem on the physical connection path.

While a faulty FC cable can cause intermittent issues, checking port error counters first provides diagnostic data to confirm if a physical layer problem exists before replacing components.

HBA topology configuration issues usually cause connection failures or consistent misbehavior from the outset, not sudden intermittent errors on an operational system.