Yes, also note that the clear thread runs for all the disks at the same position, i.e., speed will be limited by the slowest disk at that point, screenshot appears to show the end sectors of the 4TB disks, since the 3TB dis already done, so 70/80MB/s at the inner sectors for those disks is normal, probably not the controller being the bottleneck in this case, still controllers with port multipliers are not recommended for performance and stability reasons.