Some storage devices have controllers configured as primary and secondary as a part of the array configuration. The secondary paths might operate at a lower performance level than the primary paths. The multipathing feature uses the primary path to communicate with the storage device and to keep the secondary path on standby.
When the primary path fails, the Oracle Solaris I/O multipathing feature automatically directs all the I/O traffic over the secondary path, with the primary path taken offline. This process is called as failover operation. When the failure associated with the primary path is repaired, the multipathing feature automatically directs all I/O traffic over the primary path and keeps the secondary path standby as before. This process is called a failback operation.
You can disable the automatic failback operation so that the multipathing feature does not automatically failback to the primary path. When the failure associated with the primary path is repaired, you can do a manual failback operation by using the mpathadm failover command. For more information, see the mpathadm(1M) man page.