Using the C-Series IP Storage Services Modules (IPS-4, IPS-8),
Multi-protocol Services Module (14/2), and MDS 9216i
switch in an iSCSI environment
iSCSI protocol overview
iSCSI is a SCSI transport protocol for mapping of block-oriented storage data over TCP/IP networks
through iSCSI protocol data units (PDUs). The iSCSI protocol enables universal access to storage devices
and storage area networks (SANs) over standard Ethernet-based TCP/IP networks. These networks may
be dedicated networks or may be shared with traditional Ethernet applications. IP LAN/WAN routers
and switches can be used to extend the IP storage network to a wide area of applications such as
synchronous and asynchronous remote disk copy or tape backup and restore.
iSCSI in a SAN
Although the iSCSI protocol is written as a complete data transport from host to storage, this guide only
discusses the current HP supported topology of iSCSI hosts to Fibre Channel storage using the C-Series IP
Storage Services Modules (IPS-4, IPS-8) , Multi-protocol Services Module (14/2), and the 9216i switch.
Typical network structure
When you add iSCSI to a large SAN, you must configure and manage two data protocols: TCP/IP and
Fibre Channel. IP hosts with iSCSI initiators access C-Series IP Services through an IP network connected
to the C-Series Gigabit Ethernet (GbE) interface. The C-Series IP Services access Fibre Channel storage
devices connected to the Fibre Channel interfaces through the FC ports within the C-Series chassis or
through the FC ports of the IP switch.
iSCSI Initiator
With the IP Storage Services Modules (IPS-4, IPS-8), Multi-protocol Services Module (14/2), and MDS
9216i switch, the IP host uses an iSCSI initiator to enable target resource recognition and attachment.
The C-Series IP Services connect directly to HP's Fibre Channel SAN storage via an IP–to–worldwide port
number (WWPN) translation provided by the C-Series IP Services. With this transparent SCSI forwarding,
the HP Fibre Channel SAN Storage recognizes this WWPN as it would from any Fibre Channel HBA
directly connected to the SAN.
LUN setup and LUN masking can now be configured with this WWPN. The iSCSI Initiator then sees these
storage resources (LUNs) as if they were local drives attached directly to the server.
IP network
The IP network is the infrastructure used to transfer data between the iSCSI Initiator and the C-Series IP
Services via TCP/IP. LAN switches tend to be Ethernet-based, supporting speeds from 10 Mb/s to 10
Gb/s, using copper and optical interfaces ranging in size from a few ports to hundreds of ports.
LAN switches typically support TCP/IP and other protocols, including TCP/UDP, IPX, and AppleTalk.
Other features found in many LAN switches include support for voice-over-IP (VoIP), quality of service
(QoS), bandwidth management and reporting, multi-cast and jumbo frames. With the advent of SCSI
storage data now being transferred within an IP network, it is important to recognize and understand the
level of service necessary to avoid loss of data.
Part of the appeal that iSCSI brings to the storage market is low cost, standardized network adapters
and topology hardware, in addition to years of expertise developed in deploying these networks.
However, it should be stressed that existing networks must be evaluated for suitability regarding their
capacity to support iSCSI storage. In any deployment, HP recommends using a dedicated Gigabit
Ethernet network between iSCSI Initiators and the C-Series IP Storage Services Modules (IPS-4, IPS-8),
Multi-protocol Services Module (14/2), or MDS 9216i switch. This ensures adequate performance as
10
Figure 1
shows a typical IP/Fibre Channel network.
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