1. Find out the problem with the client side or server side by accessing your web application from a different machine.
2. System Level troubleshooting
a) RAM related issues
b) Disk Space related Issues
c) Disk I/O read write issues
d) Network Hardware issues
e) Mount issues
f) Too many process running in the machine
3. Application Level troubleshooting
a) Application is not behaving properly. Hit to Application log file OR application server log file OR web server Log file and try to understand the issues.
b) zombie process issues – Find out if any as such process which is causing the system performance issues.
c) Application Log – depends on the application installed, this can be referred and make use of the experience with the project and troubleshoot.
d) Web Server Log – we can check apache, tomcat log as well.
e) Memory Leak of any application – This is one of well-known issues in Linux based server due to bad application coding. Many times this can be resolved either by fixing the code or rebooting. But many other solutions are there to apply.
4. Dependent Services troubleshooting
a) SMTP Response time – SMTP server is not responding faster which is causing delay in response and queue up many processes.
b) Network issues – There are many system performance issues is dependent on network or service which is depends on the network.
c) Firewall related issues
d) Antivirus related issues
Some useful commands for system troubleshooting are
b) tail –f <logfile>
d) df –k
e) du –sh
f) ps –eaf | grep
h) iostat -x
Some useful commands for network troubleshooting are
e) netstat -tulpn/ss -tuln