<terry(at)ashtonwoodshomes(dot)com> writes:
> When my server is under heavy load I sometimes get this error (see below),
> and the backend restarts.
> FATAL 2: open of /usr/local/pgsql/data/pg_clog/0522 failed: No such file or
> directory
Is it repeatable --- that is, do you see it again if you run a VACUUM
afterwards?
If not, I'd have to speculate that you have bad RAM (or less likely, a
bad disk controller). Get out those hardware diagnostics ...
regards, tom lane