it’s not the recommended way but it’s how I’ve been doing.
you format the new drives and just cp -a -x from the running os to the destination, update the destination fstab, then treat the new drives as an os with a broken boot and continue from there.
Don’t cp, use rsync!
@CAPSLOCKFTW @anonono of I rsymc an entire drive, does it preserve all attributed and partitions, or does it just sync a particular file system.
You can only rsync a file system, you have to do the partioning beforehand. It does preserve all attributes though, if you use the right flags.