If PostgreSQL fails to start with these errors:
LOG: could not read from log file 0, segment 73, offset 0: No such file or directory LOG: invalid primary checkpoint record PANIC: could not locate a valid checkpoint record LOG: startup process (PID 1169) was terminated by signal 6: Abort trap LOG: aborting startup due to startup process failure
You can try to repair the database cluster using this command:
pg_resetxlog -f /ClusterPath
Then start PostgreSQL again. If it starts properly, you can dump the database and recreate a new one.