What is the idea behind using multiple interfaces connected to the same network (single subnet)? You should separate the different trafic types to different VLANs and IP ranges, otherwise, it is very likely that you will be experinecing what you have already described: "you only see data on one NIC".  The operating system where ScaleIO is installed has just one routing table, so it won't distinguish between more interfaces facing the same network and it will choose just one of them to send data. In consequence all packets destined to the single subnet will be leaving though one of the NICs irrespectivelly to the Scaleio roles you defined.  In other words, it is a general networking problem on the OS layer, not in the Scaleio software itself.
Hello experts   When i configure scaleIO, i use  four NIC (each use two NIC) for sds-sds and sds-sdc in the csv configuration file. The following for example:   Q1:  Could you help tell how to verify  the ip role in CLI? Q2: Two NIC are used for sds-sds, but i only see data in one NIC ,if it is normal?  Thanks in advance.
ScaleIO sds ip and sdc ip verification