pgsql-bugs(at)postgresql(dot)org writes:
> PANIC: open of /scratch/production_2/pg_clog/0996 failed: No such file or directory
I'd wonder about hardware problems, especially if this is a new server.
Messages of the above type are one of the most common consequences when
a data page has been trashed by hardware misfeasance.
(While I wouldn't sit here and swear that it couldn't be a software
problem, all of the cases I've been able to examine seemed to be
hardware failures...)
regards, tom lane