Dear Sir,
Thank you for suggesting the note. I cannot get the full information from the note but I came to know when the system is restarted it will cleanup all the files at this directory and if we set the parameters stat/level=1 and stat/max_files=48 (or)72 it will overwrite the files in that location at every time when coll_perf_stats background jobs runs in the system. I will first check this parameters in my test server and will provide you about the results.
Thanks, Regards,
Harsha.