Before starting your BU, prepare the X-drive so you don't have issues later.
Start by formatting, and making 'partitions' which are major subdivisions within the drive.
Size those to fit your usage needs. (if you do a lot of video/audio work, have 2-3 partitions for that genre, and another 2-3 smaller divisions for text or picture types of files.
If left un-partitioned, maintenance becomes tedious marathon sessions prone to disruption and/or neglect.
After you get those established, run the 'check disk' utility on each partition, to correct any platter defects.
I use "SpinRite" for this, but Windows has a disk utility as a built-in option.
Filepath is: (My) Computer> right click each drive letter drive icon (one at a time)> Properties> Tools> error check: here check both boxes, then OK.
This operation takes a while, which is one reason to have partitions in the first place; otherwise it might take hours to do at a single huge partition.
This op should be done 2X/month or so.
Migrating files can be made easier if you have within each partition folders that hold related topics, or other aspects of the files being stored that are easy to remember for you.
Then you don't have to open each folder and examine what's inside when trying to find something in particular.
One decent local B.U. application is 'Cobain' (moderately easy to use; freeware).
http://www.educ.umu.se/~cobian/cobianbackup.htm