I/O System Overview; Characteristics - IBM z13s Technical Manual

A PCIe Gen3 x16 link has these data transmission rates:
Data transmission rate per lane: 8 Gb/s * 128/130 bit (encoding) = 7.87 Gb/s=984.6 MB/s
Data transmission rate per link: 984.6 MB/s * 16 (lanes) = 15.75 GB/s
Considering the PCIe link is full-duplex mode, the data throughput rate of a PCIe Gen3 x16
link is 31.5 GBps (15.75 GB/s in both directions).
Link performance: The link speeds do not represent the actual performance of the link.
The actual performance is dependent upon many factors that include latency through the
adapters, cable lengths, and the type of workload.
PCIe Gen3 x16 links are used in z13s servers for driving the PCIe I/O drawers, and coupling
links for CPC to CPC communications.
Note: Unless otherwise specified, when PCIe is mentioned in remainder of this chapter, it
refers to PCIe Generation 3.

4.2 I/O system overview

This section lists the z13s I/O characteristics and a summary of supported features.

4.2.1 Characteristics

The z13s I/O subsystem is designed to provide great flexibility, high availability, and excellent
performance characteristics:
High bandwidth
– z13s servers use PCIe as an internal interconnect protocol to drive PCIe I/O drawers
and CPC to CPC connections. The I/O bus infrastructure data rate increases up to
16 GBps.
For more information about coupling links connectivity, see 4.9, "Parallel Sysplex
connectivity" on page 174.
– z13s servers use InfiniBand as the internal interconnect protocol to drive I/O drawers
and CPC to CPC connections. InfiniBand supports I/O bus infrastructure data rates up
to 6 GBps.
Connectivity options:
– z13s servers can be connected to an extensive range of interfaces, such as
FICON/FCP for SAN connectivity, 10 Gigabit Ethernet, Gigabit Ethernet, and
1000BASE-T Ethernet for LAN connectivity.
– For CPC to CPC connections, z13s servers use Integrated Coupling Adapter (ICA SR)
or Parallel Sysplex InfiniBand (PSIFB).
– The 10GbE RoCE Express feature provides high-speed memory-to-memory data
exchange to a remote CPC by using the Shared Memory Communications over
Remote Direct Memory Access (SMC-R) protocol over TCP.
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Link performance: The link speeds do not represent the actual performance of the
link. The actual performance is dependent upon many factors that include latency
through the adapters, cable lengths, and the type of workload.