VMware PSP is now VMW_PSP_MRU (or VNX_PSP_MRU). It was VMW_PSP_RR (or VNX_PSP_RR) before
If VirtuCache is installed, then the PSP associated with a Datastore is of the type VNX_PSP_*. If VirtuCache is not installed, then the PSP will be the VMware default PSP of the type VMW_PSP_*.
Unless the Storage Appliance vendor recommends something different, the PSP should be set to Round Robin. So if VirtuCache is installed, the PSP will be VNX_PSP_RR, if VirtuCache is not installed then the PSP will be VMW_PSP_RR.
Sometimes VMware changes the PSP back to MRU from RR, since MRU is the default VMware PSP. If this happens, you would need to change the PSP back to RR and save the configuration to make the configuration persist across reboots.
Below are the steps that you’d need to run using ESXi CLI on how to do this. The example below is when Virtucache is installed on the host, and for some reason, the PSP moved to MRU from RR, so following the below steps, you can move the PSP back to RR.
# show all claimrules added by VMware or VirtuCache userspace daemon
localcli storage nmp satp rule list | grep user
# remove the old claim rule, below example is if the PSP is VNX_PSP_MRU, which means that VirtuCache is installed and the path selection policy is ‘Most Recently Used’
localcli storage nmp satp rule remove -d
# add new claim rule, in this case we are replacing MRU with RR
localcli storage nmp satp rule add -d naa.60014055ad287fa4b78303c97b764343 -P VNX_PSP_RR -s VMW_SATP_ALUA
# do the above for all applicable LUNs
# finally save the configuration, so the config persists reboots