Hello, and thanks for replying! We've discovered that our intermittent performance issues are due to the automated backup process. I've started a new thread here: https://moodle.org/mod/forum/discuss.php?d=237841#p1032856 so I can delve into what is happening with that process a little more.
But, to answer your questions:
1) what do you mean by "slow down to halt"? Do you mean the moodle system does not respond at all while the web browser is just kept loading for a long time?
- Yes that is correct. It takes an extremely long time for page loads when we see these updates happening to the mdl_course_backup table (see screenshot above). Page loads can be up to 10-15 mins.
2) what do you do when the Moodle server is halted? restart the mysql?
- We contemplated restarting mysql however over enough time the problem seemed to fix itself and then re-occurs 1-2 days after the next automated backup occurs.
3) what is the load average of the OS when the performance problem happens?
- in all honesty I'm not sure. I've used top from time to time but we have an infrastructure group that tends to look after monitoring this kind of thing and whenever I have asked them to look into it the report back is that there are no performance issues whatsoever with cpu, memory, etc. I'm starting to look into learning more about this and capturing my own historical performance stats via top so I don't have to depend on others to give me this info.
4) when does the performance problem usually happen? when the backup is in progress ONLY?
- The automated backup process is not in progress as far as I know. That's the weird thing. It is set to run at 3 AM and I get a report indicating it has been completed successfully at 4:30 AM. Then, at around 8 AM when I get to work, I load MySQLWorkbench and see the screen full of these queries which is abnormal. Oddly enough, I sometimes continue to see the same problem the following day for a period in the morning. Then everything is fine until the next automated backup occurs and the process repeats itself.
5) how many courses and users are there in your Moodle site?
- I would have to do a query to give you exact numbers as far as users go but using the bulk user actions tool we have 6013 users that have accessed our system after September 1st of this year and we have approximately 550 courses that are active right now.