8860ch02.fm Draft Document for Review September 23, 2019 1:36 am Consider Native PCIe feature Plugging and Resource Groups (RGs) Shared Memory Communications - Direct Memory Access (SMC-D) For 10GbE RoCE Express2 or later features management details, see “RoCE Management”  on page 371. For configuration details, see 15.2.3, “Def ining a RoCE PCIe function” on page 366. The native PCIe feature support is provided by Resource Group (RG) code running on the  integrated firmware processor (IFP). For resilience, there are always four independent RGs  on the system that share the IFP. For high availability purposes, always use at least two PCIe  features located in different RGs as shown in Figure 2-4. Starting with z13 (at HW Driver level 27) and z13s servers, IBM introduced SMC-D. SMC-D  uses Internal Shared Memory (ISM) virtual PCIe adapters to provide direct memory access  communications between LPARs inside the same IBM Z CPC. SMC-D is a protocol that allows TCP socket applications to transparently use Internal Shared  Memory (ISM). ISM is a virtual channel similar to IQD for HiperSockets. A virtual adapter is  created in each z/OS LPAR and by using the SMC protocol, the memory is logically shared.  The virtual network is provided by firmware.  SMC-R requires a TCP/IP connection and preserves the entire network infrastructure.  SMC-D is also a “hybrid” solution. It uses a TCP connection to establish the SMC-D  connection. The TCP path can be either through an OSA-Express port or through  HiperSockets connection. A TCP option (called SMCD) controls switching from TCP to “out of  band” SMC-D. The SMC-D information is exchanged within the TCP data stream. Socket  Chapter 2. Planning considerations for CPC in PR/SM mode  25 Figure 2-4 Relationship among PCIe+ I/O drawer slots, domains, and RGs in the z15 –P C H I D – Virtual Function ID (VF) – Port number GLYPH<SM590000> Determine which LPARs will be shared by one RoCE Express port. GLYPH<SM590000> Assign the VFs between the sharing LPARs accordingly.