On a development Oracle environment we were running Oracle (RHEL 6.x) on a Dell PowerEdge R510 server and connected via iSCSI to a SuperMicro NAS (Nas4Free 9.1.x) on a bonded 1Gb ethernet switch (LACP on Cisco). We then changed out the one SuperMicro NAS for an updated and larger NAS and reconnected to the Oracle environment. Unfortunately we also saw attempts to contact the old/retired NAS on iSCSI.

View all iSCSI sessions
iscsiadm -m session

tcp: [2] 10.10.0.137:3260,1 iqn.2013.us.temp.zfs.freenas1:disk0
tcp: [3] 10.10.0.138:3260,1 iqn.2014.us.temp.zfs.freenas2:disk0

Logout of an iSCSI connection
iscsiadm -m node --targetname "iqn.2014.us.temp.zfs.freenas2:disk0" --logout

Logging out of session successful

Discover all available iSCSI on a host
iscsiadm -m discovery -t st -p IPADDRESSOFHOST_ORGROUP

Login to all discovered iSCSI
iscsiadm -m node --loginall=all

Login to specific iSCSI target
iscsiadm -m node -T FQN_IQN:DISK_NUMBER -l -p IPADDRESSOFHOST_ORGROUP