After applying the version (4.2.1), the administrator ran jbod_repair --backplane-self-test . The tool identified a specific PHY (physical lane) on the expander that was generating CRC errors. Using the new --remap-phy command, the patched tool disabled the faulty lane and rerouted traffic. Total downtime: 4 minutes. The patch literally saved the company from migrating 120PB to a new enclosure.