| SUSE Linux Documentation Part II. Administration / Chapter 13. iSNS for Linux Overview | ||||
|---|---|---|---|---|
 | 12.2. Configuring iSCSI Initiator | 13.2. iSNS for Linux Installation and Setup |  | |
| SUSE Linux Documentation Part II. Administration / Chapter 13. iSNS for Linux Overview | ||||
|---|---|---|---|---|
| 12.2. Configuring iSCSI Initiator | 13.2. iSNS for Linux Installation and Setup | | |
Contents
Storage area networks (SANs) can contain many disk drives that are dispersed across complex networks. This can make device discovery and device ownership difficult. iSCSI initiators must be able to identify storage resources in the SAN and determine whether they have access to them.
Internet Storage Name Service (iSNS) is a standards-based service that is available with SUSE Linux Enterprise Server (SLES) 10 Support Pack 2. iSNS facilitates the automated discovery, management, and configuration of iSCSI devices on a TCP/IP network. iSNS provides intelligent storage discovery and management services comparable to those found in Fibre Channel networks.
For an iSCSI initiator to discover iSCSI targets, it needs to identify which devices in the network are storage resources and what IP addresses it needs to access them. A query to an iSNS server returns a list of iSCSI targets and the IP addresses that the initiator has permission to access.
Using iSNS, you create iSNS discovery domains and discovery domain sets. You then group or organize iSCSI targets and initiators into discovery domains and group the discovery domains into discovery domain sets. By dividing storage nodes into domains, you can limit the discovery process of each host to the most appropriate subset of targets registered with iSNS, which allows the storage network to scale by reducing the number of unnecessary discoveries and by limiting the amount of time each host spends establishing discovery relationships. This lets you control and simplify the number of targets and initiators that must be discovered.
Both, iSCSI targets and iSCSI initiators use iSNS clients to initiate transactions with iSNS servers using the iSNS protocol. They then register device attribute information in a common discovery domain, download information about other registered clients, and receive asynchronous notification of events that occur in their discovery domain.
iSNS servers respond to iSNS protocol queries and requests made by iSNS clients using the iSNS protocol. iSNS servers initiate iSNS protocol state change notifications and store properly authenticated information submitted by a registration request in an iSNS database.
Some of the benefits provided by iSNS for Linux include:
Provides an information facility for registration, discovery, and management of networked storage assets.
Integrates with the DNS infrastructure.
Consolidates registration, discovery, and management of iSCSI storage.
Simplifies storage management implementations.
Improves scalability compared to other discovery methods.
An example of the benefits iSNS provides can be better understood through the following scenario:
Suppose you have a company that has 100 iSCSI initiators and 100 iSCSI targets. Depending on your configuration, all iSCSI initiators could potentially try to discover and connect to any of the 100 iSCSI targets. This could create a discovery and connection nightmare. By grouping initiators and targets into discovery domains, you can prevent iSCSI initiators in one department from discovering the iSCSI targets in another department. The result is that the iSCSI initiators in a specific department only discover those iSCSI targets that are part of the department’s Discovery Domain.
