Many thanks for this explanation, @oroesler.
Yes, Iin fact, I always backup with dd and at a file level.
I’ll make some trials in the direction you indicate and will report back.
What does df -h say? I see which sounds like less than you have (no warnings).
Filesystem Size Used Available Use% Mounted on
/dev/sailfish/root 2.4G 1.9G 435.4M 82% /
/dev/mapper/sailfish-home_open
49.5G 3.7G 45.3G 7% /home
Hidden or not, the home directory shouldn’t be an issue if you have 6gb free.