Chapter 18. Boot from SAN 271
18.3 Boot from SAN and other protocols
This section describes the other protocols that you can boot. Implementing them is similar to
the boot from SAN with Fibre Channel.
18.3.1 Boot from iSCSI SAN
iSCSI boot is a process in which the OS is initialized from a storage disk array across a SAN
rather than from the locally attached hard disk drive. Servers that are equipped with standard
Gigabit network adapters now can connect to SANs with complete iSCSI functionality,
including boot capabilities under Windows. Gigabit network adapters can be configured to
perform iSCSI off loading chip technology.
This technology eliminates the high up-front acquisition costs of adding storage networking to
a server. It allows IT professionals to avoid having to purchase a server with a separate HBA
controller preinstalled. In the past, IT professionals had to purchase separate controllers to
perform simultaneous data and storage networking functions. Now you can purchase a server
that is equipped with a standard network adapter that can boot iSCSI software and provide
both functions in a single network device. However, you can still install a iSCSI HBA that
offloads certain operations to its own processor. The configuration of these are comparable to
the boot from FCP.
18.3.2 Boot from FCoE
FCoE is a protocol that seamlessly replaces the Fibre Channel physical interface with
Ethernet. FCoE protocol specification uses the enhancements in Data Center Bridging (DCB)
to support the lossless transport requirement of storage traffic.
FCoE encapsulates the Fibre Channel frame in an Ethernet packet to enable transporting
storage traffic over an Ethernet interface. By transporting the entire Fibre Channel frame in
Ethernet packets, FCoE makes sure that no changes are required to Fibre Channel protocol
mappings, information units, session management, exchange management, and services.
With FCoE technology, servers that host HBAs and network adapters reduce their adapter
count to a smaller number of converged network adapters (CNAs). CNAs support TCP/IP
networking traffic and Fibre Channel SAN traffic. Combined with native FCoE storage arrays
and switches, an end-to-end FCoE solution can be deployed with all the benefits of a
converged network in the data center.
FCoE CNAs provide FCoE offload, and support boot from SAN. Configuring it is similar to the
boot from SAN with the Fibre Channel protocol.
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