If you use an external USB drive like the WD PassPort, you can format it using gparted to ext4. Which better supports the Linux file system and prevents Windows from accessing it. Which may or may not be an advantage. If you are using the drive exclusively for Linux then ext4 will work fine. gparted is given root permissions when launched and partitions formatted with it will be owned by the root. Not a problem if you are creating a snapshot with TimeShift. You can use gparted to create a second logical partition which will also be owned by the root. Using the chown command from the terminal you can change ownership to your user and group. This allows pasting files in from your home directory. Use the following steps below:
1) Use gparted to create your logical partition(s) of appropriate size. (volume must be unmounted)
2) Format the partition to ext4.
3) Mount the volume.
4) Navigate to /run/media/<user>/<folder>
Where: user is your user name. folder is the UUID assigned to the partition (usually a long hex number).
5) Open a terminal window in that folder.
6) Enter sudo chown -R <user:group> ./ (You will be prompted for a PW).
Replace user:group (no broken brackets) with your user name and users for the group (usual default group). Something like scott:users for example. The command may pause for a few seconds before returning to the prompt. You can jump up one level in the directory tree, right click on the volume's folder, select the permissions tab to check that the ownership has been changed.
An example terminal prompt from within the folder /run/media/scott mentioned above is below: (UUID is in bold)
If you get any errors when trying to unmount the volume(s), go into gparted and unmount your partition(s) there. This should allow the drive to mount/unmount normally moving forward.
If your GUI file copy gives your troubles when copying your entire home folder, you can do the following:
1) Plug in your WD PassPort drive.
2) Navigate to the partition and place you'd like your home folder to be copied.
3) Open a terminal window from the PassPort target location. (Prompt should reflect this.)
4) Enter sudo -s (You'll be prompted for a PW.)
5) Enter cp -R /home/<user> ./home
Replace <user> with your user name (less broken brackets). This will copy the entire home folder from your system and put it on the WD PassPort drive. Depending on how much data you have this will take time. Use the -v option to enter verbose mode so you can see activity.