Michael,
Can I generalize that, if after step 4) page ( new page or old page) got written disk from buffer and crash happens between step 4) and 5) we always get
block corruption issues with Postgres which can only be recovered by setting zero_damaged_pages if we just have pg_dump backups and we are OK lose data in the affected blocks?
I am also looking at ways of reproducing the issue ? appreciate your advice on it ?