Hans-Jürgen Schönig <postgres@cybertec.at> writes:
> in the past we have faced a couple of problems with corrupted system
> tables. this seems to be a version independent problem which occurs on
> hackers' from time to time.
> i have checked a broken file and i have seen that the corrupted page has
> actually been zeroed out.
That sounds to me like a hardware problem --- disk or disk controller
momentarily writing zeroes instead of what it should write. Have you
seen this on more than one physical machine? Do you have any evidence
for the implication that it only happens to system tables and not user
tables?
Also, you don't have zero_damaged_pages turned on by any chance?
regards, tom lane