IBM Power 720 Express, Обзор

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Chapter 2. Architecture and technical overview
63
2.7 PCI adapters
This section covers the types and functionalities of the PCI cards supported with the IBM
Power 720 and Power 740 systems.
2.7.1 PCIe Gen1 and Gen2
Peripheral Component Interconnect Express (PCIe) uses a serial interface and allows for
point-to-point interconnections between devices (using a directly wired interface between
these connection points). A single PCIe serial link is a dual-simplex connection that uses two
pairs of wires, one pair for transmit and one pair for receive, and can transmit only one bit per
cycle. These two pairs of wires are called a
lane
. A PCIe link can consist of multiple lanes. In
such configurations, the connection is labeled as x1, x2, x8, x12, x16, or x32, where the
number is effectively the number of lanes.
Two generations of PCIe interface are supported in Power 720 and Power 740 models:
򐂰 Gen1: Capable of transmitting at the extremely high speed of 2.5 Gbps, which gives a
capability of a peak bandwidth of 2 GBps simplex on an x8 interface
򐂰 Gen2: Double the speed of the Gen1 interface, which gives a capability of a peak
bandwidth of 4 GBps simplex on an x8 interface
PCIe Gen1 slots support Gen1 adapter cards and also most of the Gen2 adapters. In this
case, where a Gen2 adapter is used in a Gen1 slot, the adapter operates at PCIe Gen1
speed. PCIe Gen2 slots support both Gen1 and Gen2 adapters. In this case, where a Gen1
card is installed into a Gen2 slot, it operates at PCIe Gen1 speed with a slight performance
enhancement. When a Gen2 adapter is installed into a Gen2 slot, it operates at the full PCIe
Gen2 speed.
The Power 720 and Power 740 system enclosure is equipped with five PCIe x8 Gen2
full-height slots. A sixth PCIe x4 slot is dedicated to the PCIe Ethernet card that is standard
with the base system. An optional PCIe Gen2 expansion feature is also available that
provides an additional four PCIe x8 low-profile slots.
All adapters support Extended Error Handling (EEH). PCIe adapters use a different type of
slot than PCI and PCI-X adapters. If you attempt to force an adapter into the wrong type of
slot, you might damage the adapter or the slot.
Remember: The integrated console/modem port usage just described is for systems
configured as a single, system-wide partition. When it is configured with multiple partitions,
the integrated console/modem ports are disabled because the TTY console and call-home
functions are performed with the HMC.