Backup SD Card

Manual backup

It is not safe to make a backup on a running device so it is advised to power it down and take the SD Card to a PC.

Etcher

Etcher does not support a backup feature yet, check the status: https://github.com/resin-io/etcher/issues/266

dd (Linux, Mac)

dd if=/dev/mmcblk01 of=/data/backup.img bs=1M

Win32 Disk Imager (Windows)

https://sourceforge.net/projects/win32diskimager/