While VxRail is generally available with single, dual, and quad CPU sockets, SAP HANA is certified only on dual-socket and quad-socket VxRail appliances with Intel Xeon-SP (1st and 2nd generation) platinum, gold, or silver CPUs and a minimum of 12 cores per socket. Half-socket SAP HANA configurations, where two SAP HANA virtual machines share a single CPU socket, require a minimum of 16 cores per socket.

Note: Only the P-Series models are supported with Intel Xeon-SP 1st generation (Skylake).

When configuring memory for VxRail nodes to use for SAP HANA, ensure that the configuration complies with the SAP requirement for a symmetric homogeneous DIMM assembly. Also ensure that all memory channels are used, that is, six channels with
Intel Xeon-SP CPU architecture. Mixed DIMM configurations are not supported on VxRail nodes.

The following memory configurations are available for certified VxRail nodes for SAP HANA:

Table 2.              Supported memory configurations for VxRail nodes

Note: 128 GB DIMMs are supported only with Intel Xeon-SP M-type CPUs.

Because of the strict SAP requirement for a symmetric homogeneous DIMM assembly, memory sizes such as 1,024 GB or 2,048 GB are not possible with the Intel Xeon-SP CPU architecture.

Nonuniform memory access (NUMA) node sharing, the sharing of CPU sockets between SAP HANA VMs, is supported on dual-socket and quad-socket VxRail appliances. Only two production SAP HANA VMs per socket (half-socket) are allowed.

With the NUMA architecture, each processor has its local memory and can also access the nonlocal memory of the other processors over an advanced memory controller. Even with such a high-performance connection, access to local memory is always faster than access to the nonlocal memory of the other processors. Take this difference into consideration when designing and configuring SAP HANA VMs under vSphere on VxRail appliances.

Intel Optane persistent memory

VxRail solutions offer configurations that include Intel Optane persistent memory (PMem). PMem-enabled systems provide increased performance and memory capacity while maintaining data persistence for faster SAP HANA restarts at a significantly lower cost than DRAM.

For more information about the performance benefits that PMem can offer to VxRail HCI, see Dell EMC VxRail and Intel Optane Persistent Memory from Enterprise Strategy Group.

Intel Optane PMem is supported for SAP HANA on the VxRail E560F, E560N, P570F, and P580N models with Intel Cascade Lake CPUs.

Intel Optane PMem supports two addressing modes:

• Memory mode—In this mode, Intel Optane DC PMem is presented to applications and operating systems as if it were ordinary volatile memory, enabling organizations to increase memory capacity in a denser footprint and at a lower cost than DRAM. No changes to application software are required. DRAM serves as a cache for the most frequently accessed data, with PMem providing expanded main memory capacity.
• App Direct mode—App Direct mode provides data persistence during a failure, eliminating the need to recover or reload data to memory during an application or database restart. The ability to have permanent data storage in memory is what makes this architecture unique. In App Direct mode, Intel Optane PMem and DRAM are independent memory resources under the direct control of the application.

Note: SAP HANA with Intel Optane PMem is supported in App Direct mode for production and nonproduction environments. Memory mode is supported only for nonproduction environments. For more information, see SAP Note 2954515: SAP HANA Persistent Memory.

When VxRail hosts are equipped with Intel Optane PMem in App Direct (NVDIMM) mode, SAP HANA VMs can use PMem in accordance with the restrictions that are described in SAP Note 2913410: SAP HANA on VMware vSphere with Persistent Memory (access requires SAP login credentials). The VMware high availability (HA) restriction is particularly important.

The SAP HANA supported DRAM:PMem ratios and PMem DIMM sizes are:

• DRAM:PMem ratios:  2:1, 1:1, 1:2, 1:4
• PMem NVDIMM sizes: 128 GB, 256 GB, and 512 GB
  (128 GB and 256 GB PMem NVDIMMs are available now and VxRail support for
  512 GB is planned for future releases.)

The sizing of Optane PMem-enabled SAP HANA VMs is similar to that of bare-metal two-socket and four-socket SAP HANA certified servers, but with a maximum size of 6 TB (a mix of DRAM and Optane PMem) per VM. VMware recommends that SAP HANA VMs use the same DRAM:PMem ratio as the physical host/server. 

For more information about DRAM:PMem ratio sizing and preparing the VxRail nodes with PMem in App Direct mode, see the SAP HANA TDI Deployments on Dell EMC PowerEdge Servers Validation Guide.