when connecting to a host which is not up, for each discovery we will try retry_count(see kiblnd_check_reconnect) * lnet_retry_count(for resend) times.

and for each ost when mounting the mdt, we will process attach add_conn(if ost has failover node) and add_osc so 3 times discovery.

mounting of mdt when other nodes are not up can take very long, making customer think the mount is stuck.