Technicolor TG800vac - log monthly broadband usage

[Nobeard]

The 100% percent root usage is normal OpenWRT behaviour.

at my device it states:

df -h
Filesystem Size Used Available Use% Mounted on
/dev/root 8.0M 8.0M 0 100% /rom
/dev/root 8.0M 8.0M 0 100% /rom
tmpfs 124.3M 100.0K 124.2M 0% /tmp
/dev/ubi0_1 8.6M 4.3M 3.8M 53% /overlay
overlayfs:/overlay 8.6M 4.3M 3.8M 53% /
tmpfs 512.0K 0 512.0K 0% /dev

Important is the "overlayfs" which states more than 82MB free space on your device.
And even that should be enough for a database.

But you use a kind of "customised OEM-OpenWRT" on your device. Perhaps something got messed up from the manufacturer. Would be hard from over here to figure out if thats the case.