In pretty sure it will be the --dblock-size parameter, but you could double check by using the job Export link to export “As Command line…” and see what shows there.
I’ll have to get back to you on the default number of dblock (archive) files that are prepared while the “current” one is being uploaded. There’s a (poorly named?) parameter that let’s you change that count if you want.
If the tmp ramdrive is global (not just for Duplicati) then my guess is it’s getting other system filmed in they as well.
It might be worth a test run telling Duplicati to use a physical drive with known big space availability. It COULD be a “fix” but it would also help confirm this is the issue.
@kenkendk, do we know why a temp disk full error doesn’t abort the job right away?