Technical,
Once you hit enter to start the procedure you will be asked to reboot because the operation needs to have total access to all of the files on your drive and the actual procedure is done in basic after a restart.
Depending on the size of your drive, this might take some time.
So if your in a hurry, don’t start this procedure because once started, it has to run till the conversion is made.
I just finished doing this to one of my hard drives… ;D
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