I just made backup of SD card with dd command:
dd if=/dev/mmcblk0 of=backup.img bs=64k
When I started copying, Gnome Files said that there is just 8.5GB of free space from total 400GB. I forgot that I changed SD card from 8GB to 16GB, so I copied 16GB instead of 8GB. The
dd command succeed, so the remaining free space should be -7.5GB.
How is possible that the
dd didn't fail? Gnome Files said 0 bytes of free space and the file was 16GB big. I haven't tried if the file is complete or corrupted, but during copy process the size of file was changing. Did the
dd overwrite any data or was the rest stored in Cache? The
backup.img was new file and fs is ext4.
I know that GUI is not the best tool for getting info, but I was lazy.