Home > Workload Solutions > SAP > Guides > SAP HANA TDI Guides > Dell Validated Design for SAP HANA TDI with Dell PowerMax 2500 and 8500 Storage Arrays > SAN network considerations
The SAN connectivity, which includes host bus adapters (HBAs), SAN ports, switches, and array front-end ports, requires careful planning. The SAP HANA KPIs for TDI deployments require a maximum bandwidth of 400 MB/s per SAP HANA node. For example, if 52 HANA nodes in a SAN are connected to a PowerMax array, a total bandwidth of 20,800 MB/s is required. Assuming that a 32 Gbps front-end port provides approximately 3,200 MB/s of bandwidth, a minimum of eight dedicated 32 Gbps front-end ports are required to support 52 SAP HANA nodes bandwidth requirements (8 x 3,200 MB/s = 25,600 MB/s).
While this maximum bandwidth requirement arises only in the unlikely event that all nodes require the maximum bandwidth simultaneously, the ability of storage arrays to sustain this peak workload is one of the SAP HANA certification criteria.
This maximum bandwidth requirement affects more than the storage front-end configuration. In the example with 24 nodes, the complete path through the SAN network must be configured to support the maximum bandwidth. In a multihop SAN, where multiple switches are connected through Inter-Switch Links (ISLs), the bandwidth of the ISLs must also support the required bandwidth.
When you are planning storage connectivity for performance and availability, we recommend “going wide before going deep.” In other words, connecting storage ports across different node pairs and nodes is preferable to using all the ports on a single node. Even if a component fails, the storage can continue to service host I/O.
Dynamic core allocation, where each node provides services such as front-end connectivity, back-end connectivity, and data management, is available with the PowerMax arrays. Each service has its own set of cores on each node. The cores are pooled to provide CPU resources that can be allocated as necessary. For example, even if host I/O arrives through a single front-end port on the director, the front-end pool with all its CPU cores will be available to service that port. Because I/O arriving to other directors has its own core pools, for best performance and availability connect each host to ports on different nodes before using additional ports on the same node.
SAP requires isolation of the SAP HANA workload from non-SAP HANA applications. We recommend using dedicated front-end ports for SAP HANA and not sharing these ports with non-SAP HANA applications.
To connect a host or cluster, we recommend the following best practices:
Each HBA port (initiator) creates a path for I/O between the host and the SAN switch, which then continues to the PowerMax storage. Use two HBA ports, preferably on two separate HBAs. Two ports provide more connectivity and also enable the Linux native multipathing (DM-MPIO) to load-balance and fail over across HBA paths.