#### iSCSI notes

# useful packages
scsi-target-utils
iscsi-initiator-utils

# nomenclature

iscsi target = the storage device
iscsi session = the connection between the initiator and target
iscsi ports = ethernet ports which are used for communication between initiator and target
IQN = iscsi qualified name (data host)

# configuration

iscsi-iname = command to generate IQN
iscsiadm -m discovery -t st -p IP = discover iscsi targets available on data host 
iscsiadm -m node -T target_name -p IP:port --login = login to create session
iscsiadm -m node -T target_name -p IP:port --logout = log out of a session
iscsiadm -m node -T target_name -p IP:port -o update -n 'config' value = change a node db value
iscsiadm -m node -T -p -o delete = remove entry from /var/lib/iscsi/nodes
service iscsi needs to be started in order for automatic logins

# status checks

iscsiadm -m session -P{0..3} = display session settings

# gotchas

* watch out for 'duplicated' luns, etc. via multiple sessions
* 'preferred' controllers should match port IP's when logging in/out of service
* data hosts need at least 2 nics if using an array with multiple controllers
/etc/iscsi/initiatorname.iscsi = contains name of initiator; do not use iscsi-iname by default

# config locations

/var/lib/iscsi/nodes = contains node records from discovery
/var/lib/iscsi/'discovery_type' = contains records for discovery type


# target creation: add target, add logical unit, bind


# creating targets w/ tgtadm
# <driver> is usually iscsi, <id> is target ID, and <name> is iscsi-iname 

tgtadm --lld <driver> --op new --mode target --tid <id> --targetname <name> 
tgtadm --lld <driver> --op new --mode logicalunit --tid <id> --lun <lun> --backing-store <path>

# Deleting targets

tgtadm --lld <drive> --op delete --mode target --tid <id>

# listing all targets (or a specific target)

tgtadm --lld <driver> --op show --mode target (--tid <id>)

# Binding to logical unit

tgtadm --lld <driver> --op bind --mode target --tid <id> --initiator-address <address>; ALL allows all initiators to access target
tgtadm --lld <driver> --op bind --mode target --tid <id> --iniator-name <name>; specify name to allow access to target (not required)

# Portal stuff

tgtadm --lld <driver> --op show --mode portal; list portals defined on target
tgtadm --lld <driver> --op new --mode portal --param portal=n.n.n.n:3260; create new portal on target
tgtadm --lld <driver> --op delete --mode portal --param portal=n.n.n.n:3260; remove portal on target