In vmware esxi iscsi multipath is a big network degradation. What could be the problem?

Question

VMware

Colleagues, I fight iscsi multipath activ \ active in esxi and I can not defeat the problem.

Given:

1) VLAN4 (iSCSI-1) VLAN7 (iSCSI-2)
2) ESXI host (2 adapters, vDS, 2 port groups in different VLANs (iSCSI-1(id4) iSCSI-2(id7)), respectively on IP adapters from iSCSI subnets
3) Nexenta SDS with configured multipatching all in the same VLAN4,7. In storage drives SATA + SSD (RAID10).
4) On vmware, in the path settings, there is round robin to achieve active / active switching.

Everything works in this link. You disable the port on the switch, everything jumps to the live link, everything is super shorter!

Next, we start copying / moving the virtual machine from storage without multipath to storage with multipath and observe a speed of about 50mbps. We disable one of the ports on the switch that looks at the storage with multipath, VMWARE fulfills RR, one active LINK remains, the speed rises to 100-250mbps.

What could be the problem?

PS Jumbo Frames and Link Aggregation are not used.

Answer 1

Here a friend struggled with the same problem: https://forums.freenas.org/index.php?threads/iscsi...
It is stated that he overcame it. Only the storage was FreeNAS, not Nexenta.