Question is; will a mirrored raid work correctly if the data on the drives was put there through a ghosting process outside the raid then installed into a raid 1 data server?

Because the copy process can take so long with large hard drives for years when installing a mirrored raid on a data server, to save time I’ve been ghosting the data drives outside the raid then installing the drives and just starting the mirrored raid with auto rebuild enabled but without copying.

Recently I installed a mirrored NAS server and learned that at least with a mirrored NAS the mirrored raid has to be built through the copying process inside the NAS.

This made me question whether the same is true for a normal mirrored raid. I have asked a number of my normal networking friends and no one seems to know for sure.