System troubleshooting investigation checklist

Iinvestigation:

• Check nodes total, be familiar with the environment (connection flow, device/software naming).
• Check resources via monitoring command and monitoring graph.
• Check network & port connection, check the firewall.
• Check variable, naming, username, hostname, domain name.
• Check Linux processes.
• Check installation guideline/steps, operation procedures.
• Check speed (network, disk i/o, CPU, memory).
• Check log messages.
• Check software dependency (library).
• Check software environment (Linux environment)/virtual environment.
• Check user, file & directory permission.
• Check, coordinate and communicate with colleagues, supervisor, and 3rd party.
• Check user and vendor.
• Check notes.
• Check history.
• Check and crosscheck with other information.
• Check browser inspection.
• Check limitation(DB connection, java max connection, kernel max connection, etc).
• Check and run the app in debug mode.
• Check and compare with another environment, another end client.
• Check how many CPU Core
• Check Java Code CPU max, consume CPU detail, is CPU enough, be economical.
• Check Rabbitmq/message queue process.
• Check is VM Host CPU is slow.
• Check is Disk limited by the provider.
• Check developer's code
• Check with system benchmark on the idle process or reboot first.