Round Robin (RR) PSP

Creating the SATP Rule

Add the following SATP rule using the ESXi host’s console as one command:

esxcli storage nmp satp rule add --vendor="DataCore" --model="Virtual Disk"
--satp="VMW_SATP_ALUA" --psp="VMW_PSP_RR" --psp-option="iops=10"
--option="disable_action_OnRetryErrors" --claim-option="tpgs_on"
--description="DataCore SANsymphony ALUA RR"

Configuration Notes

  • Hosts must have the ALUA setting enabled in the SANsymphony console. See Changing multipath or ALUA support settings for hosts.
  • The ‘iops=10’ setting is a DataCore recommended value obtained by extensive QA testing that showed performance improvements when compared to the default value (1000). Also see: https://kb.vmware.com/s/article/2069356 to ensure that this setting persists over a reboot.
  • The ‘disable_action_OnRetryErrors’ must be explicitly set. Also see: https://kb.vmware.com/s/article/67006 to ensure that this setting persists over reboots.
  • For Round Robin PSP, DataCore recommends configuring hosts with either an explicit DataCore Server name or use the 'Auto select' setting (see ‘Notes on choosing a preferred DataCore Server below).
  • If you are trying to modify an existing SATP rule, please follow the instructions on VMware Path Selection Policies.

Choosing a Preferred DataCore Server when using Round Robin PSP
When a host's Preferred Server setting is ‘Auto Select’ the paths to the DataCore Server listed first in the virtual disk’s details tab will be set as ‘Active Optimized’. In the case of a named DataCore Server that server’s paths will be used as the ‘Active Optimized’ server, regardless of the listing order. All paths from to the other DataCore Server(s) will be set as 'Active Non-optimized'.
On using the ‘All’ setting
This will set all paths on all DataCore Servers to be ‘Active Optimized’ and while this may seem, at first, ideal it may end up causing worse performance than expected. When there is a significant distance between the DataCore Servers and the hosts (e.g., across inter-site links between remote data centers) then sending I/O Round Robin to ‘remote’ DataCore Servers may cause noticeable delays and/or latency.
Therefore, testing is advised before using the ‘All’ preferred setting in production to make sure that the I/O speeds between servers is adequate. See Appendix A – Notes on Preferred Server and Preferred Path settings for more details using the ‘All’ setting.