Hi all,
i know it`s a little late but i missed the answer to the original question to set the multipathing policy on ALL current and new datastores with esxcli (not power cli).... so you can enter it at the local ESXi shell or by ssh.
THIS SYNTAX IS VALID FOR ESXi5 ONLY!
First set the default psp for any new crated datastores to round robin (in this example for the ALUA satp (please check your array vendor)):
esxcli storage nmp satp set --default-psp VMW_PSP_RR --satp VMW_SATP_ALUA
Next use this little script to set the psp for all existing volumes to round robin.
in this example i look for volumes beginning with naa.600 (this is for HP EVA Volumes, you have to check the naa.xxx for your array vendor):
for i in `esxcli storage nmp device list | grep naa.600` ; do esxcli storage nmp device set --device $i --psp VMW_PSP_RR; done
You have to enter this command in one line!
Finally you can set the path-change-frequency from 1000 IOps (default) to 1 so every IO the other (optimized) path is used:
for i in `esxcli storage nmp device list | grep naa.600` ; do esxcli storage nmp psp roundrobin deviceconfig set -t iops -I 1 -d $i; done
Again, you have to edit the naa.xxx according to your array vendor!
I hope it helps!