As a unified storage storage system, the PowerStore system allocates block LUNs (volumes) and file systems on the same storage resources.
All block storage resources in a PowerStore system have a defined performance policy. By default, this policy is set to medium. The performance policy does not have any impact on system behavior unless some volumes are set to low performance while other volumes are set to medium or high performance. During times of system resource contention, the PowerStore system devotes fewer compute resources to volumes with a low-performance policy. Reserve the low-performance setting for volumes that have fewer critical performance needs and use the high-performance setting for all SAP HANA persistence volumes.
PowerStore block storage resources are accessed using ALUA optimized/non-optimized paths between the hosts and the two nodes within the PowerStore appliance. The PowerStore system automatically chooses one of the nodes for the optimized path when the volume is mapped to the host. This node affinity feature maintains a balanced workload across the PowerStore nodes. You can view and modify node assignment by using the PSTCLI command line. For the SAP HANA persistence (data and log) of a single SAP HANA server, it is a good practice to keep data and log assigned to alternate PowerStore nodes.
To view the current node assignment, run the following command:
pstcli -d <IP address> -u <username> -p <password> volume -name <volume name> show -output nvp | grep "ffin"
The following figure shows an example of the command output:
To change the node affinity for a volume, run this command:
pstcli -d <IP address> -u <username> -p <password> volume -name <volume name> set -node_affinity Preferred_Node_A (or Preferred_Node_B)
For best performance, it is important to balance the file system workload across both the PowerStore nodes. For the SAP HANA persistence (data and log), it is a good practice to always use two NAS servers (one on each PowerStore node) and, when creating the file systems, to distribute them evenly across the two NAS servers.