If the OS used to set up a mirror drive is changed to W7, W8 or a different install of W10, does the mirror drive has to be set up from scratch again?
If upgrading to Windows 10 (run the setup from Windows 7 or 8) it should automatically care for that. If you do a clean-install of Windows 10, then probably yes.
Do you mean I have to empty data from the two drive to start over and there is no way to use the two drive with synced data?
Take a full system backup to be on the safe side. Then try upgrading and see. If you get any problems, restore the backup, but probably you won't. Is there any way to rebuilt the RAID using Windows own Disk Management and not the third party tool? This would ensure that you can upgrade without fear.
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