If you are using MacOS, you can use Time Machine to backup your data into external drive. Time Machine will do the backup automatically when the backup drive is connected to your Mac machine.
However, if this is your first time doing Time Machine backup, it will take long time to prepare before can proceed the backup. And the initial backup should be completed less than 5-6 hours depending on how big the data you have.
Unfortunately, my case is different. My initial backup was stuck and not moving even though the machine was left the whole night. The backup stuck when it reached about 12GB.
Even with newly formatted backup drive, reboot the machine, everything, but still the initial Time Machine stuck after few minutes running.
Have you tried boot in Safe Mode?
Luckily, MacOS allows you to boot into Safe Mode. So I tried boot the machine into Safe Mode and re-run the Time Machine backup.
And it worked!
My initial Time Machine backup took about 1 hour to complete (about 300GB data). So if you are having problem with Time Machine and the initial backup took years to complete, try boot it in Safe Mode and re-run the backup process.
I am not really sure why, but most probably there might be some applications were blocking the Time Machine to do the backup. And when booted in Safe Mode, the Time Machine can perform the backup without any interruption.