In a productional environment, you never do a software based raid, instead you have a dedicated controller. Also, usually you don't use 2 tb for each disks because of perfomances are really poor.
If you right click DISK MANAGEMENT and then click on REFRESH you have the same result?!
Microsoft cannot add a "pause" button because of the thing is managed by SOFTWARE. So, once the OS is turned off, the raid cannot be monitored anymore.
3GB/s doesn't mean anything... remember that your BUILT-IN RAID is managed by the same chipset, so your 3 GB/s must be divided by normal disk usage, raid rebuild. In a normal condition (2 SEPARATE DISKS), try to copy 1 GB file from disk A to B, your speed will never be 3 GB/s, instead 20-30 MB/s right? Right!
So, if you want more performances, switch to a dedicated RAID CONTROLLER (a good one costs about 200$).