If your initiator cannot connect to your target:
Make sure the IQN of the initiator matches the IQN identified in the initiators list.
Check that IP address of iSNS server is correct and that the iSNS server is configured.
Check that the IP address of the target is correct on the initiator side.
Check that initiator CHAP names and secrets match on both sides.
Make sure that the target CHAP name and secret do not match those of any of the initiators.
Check that the IP address and secret of the RADIUS server are correct, and that the RADIUS server is configured.
Check that the initiator accessing the LUN is a member of that LUN's initiator group.
Check that the targets exporting that LUN are online.
Check that the LUN's operational status is online.
Check the logical unit number for each LUN.
If, during the failover / failbacks, the iSER Reduced Copy I/Os from the Red Hat client are not surviving:
Modify the node.session.timeo.replacement_timeout parameter in the /etc/iscsi/iscsid.conf file to 300sec.