For iSCSI, if the targets send an iSCSI async event indicating new storage is added, then the scan is done automatically. However, if the targets do not send an iSCSI async event, you need to manually scan them using the iscsi adm utility. Before doing so, however, you need to first retrieve the proper --targetname and the --portal values. If your device model supports only a single logical unit and portal per target, use iscsiadm to issue a send targ ets command to the host, as in:

# iscsiadm -m discovery -t sendtargets -p target_IP:port

The output will appear in the following format:

target_IP:port,target_portal_group_tag proper_target_name

Using iscsiadm to issue a send targets command


For example, on a target with a proper_target_name of iqn.1992-08. com.netapp: sn. 336 15311 and a target_IP:port of 10.15.85.19 : 326 0 , the output may appear as:

10.15.84.19:3260,2 iqn.1992-08.com.netapp:sn.33615311
10.15.85.19:3260,3 iqn.1992-08.com.netapp:sn.33615311

In this example, the target has two portals, each using target_ip:ports of

10.15.84.19:326 0 and 10.15.85.19:326 0

To see which i face configuration will be used for each session, add the -P 1 option. This option will print also session information in tree format, as in:

Target: proper_target_name
Portal: target_IP:port,target_portal_group_tag
Iface Name: iface_name

View iface configuration

For example, with

iscsiadm -m discovery -t send targets -p 10.15.85.19:326 0 - P 1

the output may appear as:

Target: iqn.1992-08.com.netapp:sn.33615311
Portal: 10.15.84.19:3260,2
Iface Name: iface2
Portal: 10.15.85.19:3260,3
Iface Name: iface2

This means that the target iqn.1992-08.com.netapp: sn.336 15311 will use iface2 as its iface configuration.
With some device models a single target may have multiple logical units and portals. In this case, issue a send targ ets command to the host first to find new portals on the target. Then, rescan the existing sessions using:

# iscsiadm -m session --rescan

You can also rescan a specific session by specifying the session's SID value, as in:

# iscsiadm -m session -r SID --rescan⁠

If your device supports multiple targets, you will need to issue a send targ ets command to the hosts to find new portals for each target. Rescan existing sessions to discover new logical units on existing sessions using the --rescan option.
Important
The send targets command used to retrieve --targ etname and --portal values overwrites the contents of the /var/lib/iscsi/nodes database. This database will then be repopulated using the settings in /etc/iscsi/iscsid.co nf. However, this will not occur if a session is currently logged in and in use.

To safely add new targets/portals or delete old ones, use the -o new or -o delete options, respectively. For example, to add new targets/portals without overwriting /var/lib/iscsi/nodes, use the following command:

iscsiadm -m discovery -t st -p target_IP -o new

To delete /var/lib/iscsi/nodes entries that the target did not display during discovery, use:

iscsiadm -m discovery -t st -p target_IP -o delete

You can also perform both tasks simultaneously, as in:

iscsiadm -m discovery -t st -p target_IP -o delete -o new

The send targ ets command will yield the following output:

ip:port,target_portal_group_tag proper_target_name

Output of the send targets command

For example, given a device with a single target, logical unit, and portal, with equal logici scsi 1 as your target_name, the output should appear similar to the following:

10.16.41.155:3260,0 iqn.2001-05.com.equallogic:6-8a0900-ac3fe0101-63aff113e344a4a2-dl585-03-1

Note

that proper_target_name and ip:port,target_portal_group_tag are identical to the values of the name
At this point, you now have the proper --targ etname and --portal values needed to manually scan for iSCSI devices. To do so, run the following command:

# iscsiadm --mode node --targetname proper_target_name --portal ip:port,target_portal_group_tag --login

Full iscsiadm command

Using our previous example (where proper_target_name is equal logic-iscsi 1), the full command would be:

# iscsiadm --mode node --targetname iqn.2001-05.com.equallogic:6- 8a0900-ac3fe0101-63aff113e344a4a2-dl585-03-1 --portal
10.16.41.155:3260,0 --login