Fibre Channel Over Ethernet - Compaq BL10e - HP ProLiant - 512 MB RAM Introduction Manual

iSCSI protocol, such as a tape drive. The iSCSI stack at both ends of the path is used to encapsulate
SCSI block commands into Ethernet Packets for transmission over IP networks as illustrated in Figure 3.
Figure 3. iSCSI is SCSI over TCP/IP
File System
Disk Driver
SCSI
SCSI MP**
Direct attached block
storage using
SCSI/SAS *
* Serial Attached SCSI
** Multipathing
Initiators include software initiators and Host Bus Adapters (HBAs). Software initiators require CPU
resources to manage the protocol stack. A more efficient approach is to offload the protocol
management to an iSCSI HBA. The operating system sees an iSCSI HBA as a SCSI HBA.
IP-based networks can drop data. To compensate for any dropped data, iSCSI maintains a buffer for
the entire network bandwidth. This can increase the latency of the end-to-end round-trip transport and
can require large buffers.

Fibre Channel over Ethernet

Fibre Channel over Ethernet (FCoE) is an emerging 10GbE fabric already embraced by some network
hardware vendors. FCoE encapsulates Fibre Channel frames within the Ethernet fabric. FCoE uses the
same Open Systems Interconnection (OSI) layer as IP networks. The following are some of the
advantages that come with FCoE implementation:
FCoE utilizes FC drivers, switches, and other infrastructure
Existing FC security and management applications are unchanged
FCoE provides a 10Gigabit Ethernet fabric with potentially no data loss, compared to IP based
networks
Existing SAN management tools can be used to access storage
FCoE can utilize enhanced Ethernet features like traffic priority and flow control
iSCSI initiator
File System
Disk Driver
SCSI
iSCSI MP**
TCP/IP
Ethernet
Ethernet
Ethernet
iSCSI target
iSCSI
TCP/IP
Ethernet
Remote block storage using iSCSI
SCSI
8