Editing Internet Storage Name Service (section)

== Services ==

An iSNS implementation provides four primary services:

*Name registration and storage resource discovery
*Discovery domains and login control
*State-change notification
*Bidirectional mappings between Fibre Channel and iSCSI devices

=== Name registration and storage resource discovery ===

iSNS implementations allow all entities in a storage network to register and query an iSNS database. Both targets and initiators can register with the iSNS database, and each entity can inquire about other initiators and targets. For example, a client initiator can obtain information about target devices from an iSNS server.

=== Discovery domains and login control ===

Administrators can use the discovery domains to divide storage nodes into manageable, non-exclusive groups. By grouping storage nodes, administrators are able to limit the login process of each host to the most appropriate subset of targets registered with the iSNS, which allows the storage network to scale by reducing the number of unnecessary logins and by limiting the amount of time each host spends establishing login relationships.

Each target is able to use login control to delegate their access control and authorization policies to an iSNS server. Such delegation is intended to promote centralized management.

=== State-change notification ===

The state-change notification (SCN) service allows an iSNS server to issue notifications about each event that affects storage nodes on the managed network. Each iSNS client may register for notifications on behalf of its storage nodes, and each client is expected to respond according to its own requirements and implementation.

=== Bidirectional mappings between Fibre Channel and iSCSI devices ===

Because the iSNS database stores naming and discovery information about both Fibre Channel and iSCSI devices, iSNS servers are able to store mappings of Fibre Channel devices to proxy iSCSI device images on the IP network. These mappings may also be made in the opposite direction, allowing iSNS servers to store mappings from iSCSI devices to proxy [[World Wide Name]]s (WWNs).