>> Our topology is 2 NIC's, 1 for vmotion and 1 for storage, and also 2 Vlans, 1 vlan for vmotion without any IP address, and the storage vlas with IP address, if one of the NIC's failed, the second backing up.
i understood that maybe the problem is because vMotion Vlan is without IP, and the traffic goes toward storage NIC, are you think it can be the problem?
maybe update our Dell servers NIC's drivers?
So you have one vSwitch with two vmkernel ports (one for vMotion and one for storage). Do you have unique subnets assigned to the vmkernel ports?