iSNS for Linux Overview
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iSNS for Linux Overview
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 1. 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.
This overview contains the following sections:
Section 1.1, “How iSNS Works,” on page 9
Section 1.2, “Benefits of iSNS,” on page 10
Section 1.3, “What's Next,” on page 10
1.1 How iSNS Works
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 login 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 logins and by limiting the amount of time
each host spends establishing login relationships. This lets you control and simplify the number of
targets and initiators that have access to each other.
Figure 1-1
iSNS Discovery Domains and Discovery Domain Sets
iSNS clients initiate transactions with iSNS servers using the iSNS protocol. They then register
device attribute information in a common discovery domain, download information about other
Discovery
Domain
Set
Discovery
Domain
Target
Target
Target
Initiator
Initiator
Nodes
Target and
Initiator
