Failover Timers
| Parameter | Recommended | Effect |
|---|---|---|
fast_io_fail_tmo |
10 seconds | Time to fail I/O after fabric reports link down |
dev_loss_tmo |
60 seconds | Time before device is removed after persistent failure |
failback |
immediate |
Restore preferred paths as soon as they come back online |
Testing Path Failover
# Disable one path (replace sdb with actual device)
echo offline | sudo tee /sys/block/sdb/device/state
# Verify multipath reroutes
sudo multipath -ll
# Re-enable the path
echo running | sudo tee /sys/block/sdb/device/state