Disk space needed higher than expected about openethereum HOT 2 CLOSED

For the benefit of everyone who might experience the same issue, I could solve it :
I restored the database as it was before running the migration tool (version 15)
Then I ran Openethereum 3.0.1 without any peers (max_peers=0).
After about 24 hours disk usage started to go down, and about 12 hours later garbage collection was done ! 355 GB instead of 567 GB

~$ df
Filesystem     1K-blocks      Used Available Use% Mounted on
...
/dev/nvme1n1   618222752 355431560 235973672  61% /home/ubuntu/.local

Finally I could run the migration tool again and start using Openethereum 3.1

from openethereum.

This is one of the reasons why we decided to make v3.1 from a v2.5.13 base.

from openethereum.