As a unified storage array, 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 policy for volumes that have fewer critical performance needs and set the policy to high performance for all SAP HANA persistence volumes.
Appliance balance for SAP HANA block storage workloads
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 best 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:
Figure 7. View node affinity command (example)
To change the node affinity for a volume, run:
pstcli -d <IP address> -u <username> -p <password> volume -name <volume name> set -node_affinity Preferred_Node_A (or Preferred_Node_B)