Home > Workload Solutions > Oracle > Best Practices > Intel-Based Oracle Best Practices on Dell PowerEdge R740 and PowerMax 2000 > Storage Best Practices > Day One Best Practices > VMware ESXi: Round Robin Path Policy
Round Robin path policy defines how to balance I/O load across active storage paths. In this best practice, the Round Robin path policy will be changed to optimize performance.
Category | PowerMax Storage |
Product | VMware ESXi |
Type of best practice | Performance Optimization |
Day and value | Day 1, Highly Recommended |
Overview
At the hypervisor layer, ESXi controls the flow of data to and from the server. There are several configuration choices including Most Recently Used (MRU), Fixed, and Round Robin. In this best practice, changes are made to the Round Robin path policy to optimize data path usage between the PowerEdge servers and the PowerMax storage.
Round Robin automatically rotates through all available paths to distribute the data flow. As PowerMax has all active paths to storage, Round Robin will rotate data across those pathways. By default, Round Robin sends 1,000 I/O operations across one path before using the next path. In this best practice, we change the default of 1,000 to 1. With a Round Robin IOPS limit of 1, the paths to storage will be rotated more frequently, thus providing a positive impact upon storage performance.
Recommendation
Changing the Round Robin Path Policy to 1 showed a significant performance improvement. Test findings showed significant improvements for:
NOPM and TPM increased when compared to the prior test, indicating the change to the Round Robin path policy improved performance. Server CPU utilization also increased.
An increase in PowerMax IOPS indicates more efficient use of I/O paths to storage. Optimal path usage benefits the database as the response times for reads and writes decrease.
Server processor utilization can be impacted by default settings that are not optimized. In this case, the default Round Robin setting of 1,000 I/O before moving to the next path was impacting performance. Changing the Round Robin setting to 1 I/O before moving to the next path resulted in a more frequent path switch rate, thereby improving performance. An increase in server CPU utilization indicates reduced storage wait time and more efficient processor utilization.
Both DB File Sequential Read and Log File Parallel Read Write are database metrics that indicate database performance. A decrease in both metrics shows the database is receiving data faster.
Overall, the best practice of changing the Round Robin path policy from 1,000 I/Os to 1 is highly recommended and should be considered as a Day 1 practice as part of initial data provisioning.
Implementation Steps
To configure Round Robin I/O operations from 1,000 to 1, login into the ESXi SSH console and run the following command using esxcli:
for i in `esxcfg-scsidevs -c |awk '{print $1}' | grep naa.xxxx`; do esxcli storage nmp psp roundrobin deviceconfig set --type=iops --iops=1 --device=$i; done
Verify the change using the following command:
esxcli storage nmp device list
Additional Resources
This best practice was referenced from the VMware Multipathing policies in ESXi/ESX and Adjusting Round Robin IOPS limit from 1000 to 1.