Good afternoon to everybody, I would like to ask about a problem I have and which I'm not able to solve it.
I have two servers, one is the web server (it contains a large web application) and the other one is the BD server.
The problem is that both are virtualized in a physical server with VMWare and they were running correctly until two weeks ago. In the start of this month we noticed that the web application ran very slow and we started to investigate what was the problem. We have tried a lot of things and we do not know what is the problem and, of course, how to solve it.
Both servers has an internal IP and only web server is accessible from Internet. Only web server access to BD server in order to get the results of queries. It's true that web server and BD server has an older versions of PHP and MySQL respectively.
We did the following tests:
- Analyze the consumption of both servers. They are in 1% of memory, swap and al types of consumptions. Our physicial server is new from a year ago and both virtual servers does not use more than 5% of their resources.
- Reboot both servers
- Reboot physical server (VMWare server)
- Restore a backup from 1 and 2 months ago of both servers to discard code and BD data errors
- Review code (we do not touch code from before the error)
We did some queries from terminal's webserver and they were fast. We looked for the BD log and we could see that queries have been doing one by one in a "slow" velocity (0,5s for query aprox, depending on the query it can be more than a second).
We suspect that PHP is doing something bad, but we do not touch the code and we do not update PHP version or MySQL version. We want to try to update MySQL version in a new virtual machine and migrate all the data there, but we think it will not solve the problem.
The connection between servers is perfect and we think that layer 2 should not be the problem. In the same webserver we have another web application (Moodle) that connects to this BD server too, and it does not have this problem...
What can be the problem? It's very strange this change of behaviour of the web application. We were on holidays on August and we returned and we found this problem.
For more information we use PHP 5.6.40 (webserver) and MySQL Ver 14.14 Distrib 5.1.60, readline 5.1 (BD server). (yes, we know they are old versions but the web application and BD are old too)
I hope someone can help us, we are a little bit lost.
Thanks for your help!