iSCSI is an emerging standard for SCSI block storage protocols networked over high-speed TCP/IP networks. iSCSI lets you create a low-cost Storage Area Network (SAN) using commodity high-speed Ethernet hardware. iSCSI provides significant cost savings when compared to the costs required to create a fibre channel SAN.
Currently, Novell® SANs consist of storage devices purchased from third-party storage vendors. Most SANs are constructed using fibre channel devices and storage arrays. A fibre channel host bus adapter is installed into each NetWare® server and connects each server to a fibre channel switch and external shared storage arrays. The SAN consolidates storage resources for servers running NetWare. RAID sets or individual disk drives located inside centralized storage arrays are exclusively assigned to individual servers in order to emulate direct-attached disks dedicated for each server, or they are assigned to and shared by multiple servers if running cluster software like Novell Cluster Services™. The following figure shows how a typical fibre channel SAN configuration might look.
Figure 1-1 Typical Fibre Channel SAN Configuration
The configuration illustrated above creates two separate networks and corresponding management domains. One is the fibre channel SAN dedicated to storage. The other is the traditional local area network that carries file, messaging, Web, LDAP, and other standard client/server protocol packets that clients of NetWare servers use to interact with Novell services.
NetWare iSCSI allows a SAN to be built using the same hardware and management domain that is used in a traditional LAN. An iSCSI SAN can use the same infrastructure as the LAN or it can have its own dedicated infrastructure.
NetWare iSCSI consists of software that you add to your existing NetWare servers. It lets you use existing hardware on your NetWare network to create a SAN and a NetWare cluster.
NetWare iSCSI software is divided into two parts:
Initiator software is installed and configured on servers in the SAN that will be used to access shared storage. Initiators can be cluster servers. Initiators use the iSCSI protocol to communicate with an iSCSI storage server or target over a TCP/IP network.
Target software is installed on a NetWare server and provides access to shared disks through the iSCSI protocol. iSCSI target software enables the server where it is installed to function as a disk controller for the shared disk system.
The following figure shows how a typical iSCSI SAN configuration might look.
Figure 1-2 Typical iSCSI SAN Configuration
iSCSI storage routers perform the same function as an iSCSI target server. If you are using an iSCSI storage router, NetWare iSCSI target software is not needed.