When using the Round Robin Path Selection Policy it is necessary, for performance reasons, to change the Round Robin IOPS limit to 1 (default is 1000). This setting will determine the number of IOPS VMWare will issue before switching to the next available path.
Round Robin IOPS limits are configured on a per-device basis. To configure the Round Robin IOPS limit of all Zadara Storage devices run the following command on each ESX host.
for i in `esxcli storage nmp device list | grep "Zadara" | cut -d '(' -f2 | cut -d ')' -f1`; do esxcli storage nmp psp roundrobin deviceconfig set --type=iops --iops=1 --device=$i; done
For more information please see: https://kb.vmware.com/s/article/2069356