I have an Ubuntu 12.04 with an external 1.5T disk (just for data). It is /dev/sdc1 seen below:

$ df -T
Filesystem        Type      1K-blocks      Used  Available Use% Mounted on
/dev/sda1         ext4     1451144932  27722584 1350794536   3% /
udev              devtmpfs    6199460         4    6199456   1% /dev
tmpfs             tmpfs       2482692       988    2481704   1% /run
none              tmpfs          5120         0       5120   0% /run/lock
none              tmpfs       6206724       284    6206440   1% /run/shm
/dev/sdc1         fuseblk  1465135100 172507664 1292627436  12% /media/Elements

The thing is I would like to implement this rsync-based backup strategy and I want to use my /dev/sdc1 external drive for that. Since the guide mentioned above recommends placing the backup directory in a separate partition I want to repartition the /dev/sdc1 external hard disk but retain existing data in a separate partition. E.g. split /dev/sdc1 into two partitions: (i) one to be used exclusively for the rsync-based backup and (ii) the other for the existing miscellaneous data. How should I go about partitioning with minimal risk to my existing data and what kind of filesystem do you recommend? I would prefer a console-based guide but unfortunately all the material I found on the web is oriented towards partitioning the main (bootable) disk and not an external fuseblk filesystem used only for passive data.