this is obsolete doc -- see http://doc.nethence.com/ instead

Configuring an iSCSI initiator on RHEL5/6 

Requirements 

Make sure the iSCSI initiator software is installed, 

rpm -q iscsi-initiator-utils

Enable the deamons, 

chkconfig iscsi on

chkconfig iscsid on

service iscsi restart

service iscsid restart

service iscsi status

service iscsid status

Make sure the Disk Array allows your initiator to connect. Show your initiator IQN, 

cut -f2 -d'=' /etc/iscsi/initiatorname.iscsi

Register target iSCSI LUNs 

Show the available LUNs, 

iscsiadm -m discovery -t sendtargets -p DISK_ARRAY_IP

Show information and connect to a LUN, 

iscsiadm -m node -T IQN -p DISK_ARRAY_IP

iscsiadm -m node -T IQN -p DISK_ARRAY_IP -l

Note. to connect to all LUNs at once, 

#iscsiadm -m discovery -t st -l

Unregister target iSCSI LUNs 

See the current iSCSI sessions, 

iscsiadm -m session

disconnect from all LUNs, 

iscsiadm -m node -U all

disable at next boot, 

iscsiadm -m node -T <IQN> -p <IP_ADDRESS> --op delete

Other nodes 

When you resize the LUN on the Disk Array, rescan, 

iscsiadm -m session --rescan

Note. The good old way for Fiber Channel was, 

#echo "- - -" > /sys/class/scsi_host/host0/scan

References 

https://access.redhat.com/knowledge/solutions/6387 (login needed)