BackinTime is using a huge amount of system IO-ressources -> use LVM snapshots and just do one BackInTime Backup on the external USB

For Backup, I created a LVM snapshot each hour and let BackinTime make
a backup on an external USB disk.

But this caused the usage of very heavy system usage on the IO system of
Linux, because of the size it run also about 20 minutes.

To get a better response, I changed the tactics.

Let LVM do snapshots every hour and keep only some of them and just do
for one time a backup on the external disk with BackinTime.

For the regular snapshots I found a script in this blog.

Now I'm doing regular snapshots, mount the last snapshot on /backup
and let BackInTime do one sync to the external disk.

This reduces the IO-Load.