Chapter 11. SAN connections and configuration 461
Figure 11-2 shows the SAN area to be examined in this section. Primarily, it details
connections within the IBM Flex System Enterprise Chassis, but also looks at connectivity to
external storage and configuration of the I/O switch modules.
Figure 11-2 SAN Connectivity within the IBM Flex System Enterprise Chassis
11.3 iSCSI connectivity
The Internet Small Computer System Interface (iSCSI) protocol is the encapsulation of the
industry standard SCSI protocol within TCP/IP packets. The iSCSI protocol provides a
block-level storage capability similar to Fibre Channel (FC) storage area network (SAN)
technology. It is essentially the same system of encapsulating the SCSI protocol within an
external “carrier.” The difference is that the iSCSI SAN uses Ethernet instead of FC transport
technology. The iSCSI protocol uses TCP to transport SCSI I/O commands over a network. It
provides block-level data access where it encapsulates SCSI commands into protocol data
units (PDUs) within the TCP/IP protocol, and then transports them over the network to the
target device.
iSCSI transactions occur between an iSCSI initiator (hardware or software) that transmits a
request (such as read/write) and an iSCSI target. This iSCSI target processes the request
and responds with the appropriate information, such as data and sense. The initiating device
in the Flex System environment is the compute node and the target devices are the IBM Flex
System V7000 Storage Node canisters. The connectivity between the initiator and target is
shown in Figure 11-1 on page 460 and detailed in that section. The type of connectivity would
be determined also by the compute node platform, operating system and its device drivers.
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