An iSNS server uses the Internet Storage Name Service (iSNS) protocol to maintain information about active iSCSI devices on the network, including their IP addresses, iSCSI node names (IQNs), and portal groups.

The iSNS protocol enables automated discovery and management of iSCSI devices on an IP storage network. An iSCSI initiator can query the iSNS server to discover iSCSI target devices.

The iSNS server communicates with each storage virtual machine (SVM) through the SVM management LIF. The management LIF registers all iSCSI target node name, alias, and portal information with the iSNS service for a specific SVM.

In the following example, SVM “VS1” uses SVM management LIF “VS1_mgmt_lif” to register with the iSNS server. During iSNS registration, an SVM sends all the iSCSI LIFs through the SVM management LIF to the iSNS Server. After the iSNS registration is complete, the iSNS server has a list of all the LIFs serving iSCSI in “VS1”. If a cluster contains multiple SVMs, each SVM must register individually with the iSNS server to use the iSNS service.

In the next example, after the iSNS server completes the registration with the target, Host A can discover all the LIFs for “VS1” through the iSNS server as indicated in Step 1. After Host A completes the discovery of the LIFs for “VS1”, Host A can establish a connection with any of the LIFs in “VS1” as shown in Step 2. Host A is not aware of any of the LIFs in “VS2” until management LIF “VS2_mgmt_LIF” for “VS2” registers with the iSNS server.

However, if you define the interface access lists, the host can only use the defined LIFs in the interface access list to access the target.

After iSNS is initially configured, ONTAP automatically updates the iSNS server when the SVM configuration settings change.

A delay of a few minutes might occur between the time you make the configuration changes and when ONTAP sends the update to the iSNS server. Force an immediate update of the iSNS information on the iSNS server:
vserver iscsi isns update

ONTAP provides commands to manage your iSNS service.

See the man page for each command for more information.