I have seen where the iSCSI initiators will drop the connections due to the fact of a slow response time from the Target or the speed, and if your doing some replications what is the speed of the volume replication link (please dont share this link w/ other services).

Or RAID could be doing something on the backend like RAID health check or disk or BBU check, slows the performance and if every one is hammering it could cause a delay but we would have to see the logs or check the 3Ware logs.