Technologies in HP ProLiant Gen8 c-Class server blades

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pair to transmit data at the signaling rate in both directions simultaneously. ProLiant Gen8 server blades support PCIe
3.0 slots (PCIe 2.0 in the BL465c), which have a signaling rate of 2.5 Gb/s per direction per lane. After accounting for 20
percent serializing/deserializing encoding overhead, the resulting effective maximum bandwidth is 2 Gb/s (250 MB/s)
per direction per lane. Therefore, a x4 link with 4 send and receive pairs has an effective bandwidth of 2 GB/s. A x8 link
has an effective bandwidth of 4 GB/s. This flexibility allows slower devices to transmit on a single lane with a relatively
small number of pins while faster devices can transmit on more lanes as required. The PCIe 3.0 technology on the
ProLiant BL420c, BL460c, and BL660c Gen8 server blades offer improved latency and up to 400 percent bandwidth per
I/O expansion slot3.
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Serial Attached SCSI technology
SAS is a serial communication protocol for direct-attached storage devices such as SAS and SATA Small Form Factor
(SFF) and Large Form Factor (LFF) disk drives. It is a point-to-point architecture in which each device connects directly to
a SAS port rather than sharing a common bus, as parallel SCSI devices do. Point-to-point links increase data throughput
and improve the ability to locate and fix disk failures. More importantly, SAS architecture solves the parallel SCSI
problems of clock skew and signal degradation at high signaling rates.
Optional mezzanine cards
HP offers a variety of optional mezzanine cards to connect to outside networks and storage. HP ProLiant c-Class server
blades support up to two mezzanine cards (half height servers) and three mezzanine cards (full height servers) that
connect to the various interconnect fabrics such as Fibre Channel, Ethernet, serial-attached SCSI, and InfiniBand. Type A
and Type B mezzanine cards differ only in the amount of power allocated to them by the server and in the physical space
they occupy on the server blade. Type A mezzanine cards have slightly less power available to them and are slightly
smaller. Type A mezzanine cards are compatible with all mezzanine connectors in ProLiant Gen8 c-Class server blades.
Type B mezzanine cards are compatible with Mezzanine 2 or 3 connectors in full-height ProLiant Gen 8 c-Class server
blades. Type B mezzanine cards are also compatible with Mezzanine 2 connectors in half-height ProLiant Gen 8 c-Class
server blades.
Both types of mezzanine cards use a 270-pin connector, enabling up to eight lanes of differential transmit and receive
signals. Because the connections between the device bays and the interconnect bays are hard-wired through the signal
midplane, the mezzanine cards must be matched to the appropriate type of interconnect module. For example, a Fibre
Channel mezzanine card must be placed in the mezzanine connector that connects to an interconnect bay holding a Fibre
Channel switch. For the most up-to-date information about the c-Class mezzanine card options, go to the HP website:
http://h18004.www1.hp.com/products/blades/components/c-class-interconnects.html.
Network and virtualization technologies
Multifunction 1 Gb or 10 Gb Ethernet FlexibleLOM adapters on all c-Class server blades provide several advantages.
TCP/IP Offload Engine (TOE) - The increased bandwidth of Gigabit Ethernet networks increases demand for CPU cycles
to manage the network protocol stack. This means that performance of even a fast CPU will degrade while
simultaneously processing application instructions and transferring data to or from the network. Computers most
susceptible to this problem are application servers, web servers, and file servers that have many of concurrent
connections.
The ProLiant TCP/IP Offload Engine for Windows speeds up network-intensive applications by offloading TCP/IP-related
tasks from the processors onto the network adapter. TOE network adapters have on-board logic to process common and
repetitive tasks of TCP/IP network traffic. This effectively eliminates the need for the CPU to segment and reassemble
network data packets. Eliminating this work significantly increases the application performance of servers attached to
gigabit Ethernet networks.
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Per HP internal testing, compared to a ProLiant BL460c G7 x8 PCI Gen 2 expansion slot. Actual results will depend on application, system configuration
and tuning.