Home > Workload Solutions > SAP > Guides > SAP HANA HCI Guides > Dell Validated Design for SAP HANA Deployments with Dell VxRail Infrastructure > Appendix B: VxRail stretched cluster validation environment
The two-site VxRail vSAN stretched cluster was built in Dell Technologies labs and validated for SAP HANA by Dell Technologies and VMware. The team installed a WAN emulator physical host to isolate the vSAN traffic between the two sites in the cluster, enabling the introduction of different levels of latency between the sites to measure the performance impact for different distances.
To calculate cable distances between the two sites, the Dell SAP engineering team used 5 ms per kilometer in accordance with the Calculating Optical Fiber Latency reference tool.
The team used a cluster of four P570F VxRail nodes on site A and four P570F VxRail nodes on site B, and then deployed the nodes in a vSAN stretched cluster, as shown in the following figure.
Each site had six SAP HANA VMs, with two per P570F node and one P570F node as a standby. The stretched cluster had a total of 12 SAP HANA VMs across the two sites.
The team used the SAP HANA Hardware and Cloud Measurement Tool (HCMT) to perform tests on the 12 SAP HANA VMs in parallel. The goal was to ensure that the performance of the SAP HANA and vSAN stretched cluster was compliant with the SAP HANA sub-millisecond log latency KPI and VMware stretched cluster requirements.
The team conducted the HCMT tests over zero distance initially to establish a baseline, and then over various short distances. This was done to measure the performance impact on the SAP HANA KPIs as the latency was introduced. The test results showed that it was possible to achieve distances of up to 30 km between the two sites and still meet the SAP HANA sub-millisecond log latency KPI.
The Dell SAP validation team configured four P570F nodes on site A and four P570F nodes on site B with:
Two 25 GBe Ports on Dual Port PCIe for vSAN/vMotion traffic
Two 25 Gb Dell LAN-switches (TOR switches): Dell S5148 with 25 GbE ports (autonegotiation to 10 GbE is possible)
vSAN 7.0 U1 stretched cluster