esxi + v3700 multipath error

Hello,

For learning purposes I use V3700 (P/N 00MJ095) and Dell 1950  (Emulex LPe12002 card is installed into the Dell Server) to configure multipath on esxi, I use Volume from V3700 as Hdd  and I installed esxi 6 on it and it worked thenI configured multipath on esxi with PSP (Round Robin) as images below (image 1,2,3)  but when i uploaded iso file to Datastore, it shows xxxx minute(s)..... and very slow (image 4) but if i used singe path and it uploaded very fast.

Image

1)

2)

3)

4)

I also checked article at VMware Knowledge Base  and Adjusting Round Robin IOPS limit from default 1000 to 1  but the problem still persists.

Anyone can help me how to configure multipath correctly ?

Thank you.

Sang.