Lecture #13 Monitoring System Performance

Learner Outcomes

• Explain the use of the uptime, ps, top, and kill commands.
• Use vmstat to collect information about system performance
• Kill zombie and other wayward processes
• View and edit the syslog.conf file to find valuable log files
• Create a cron file to automate a repetitive task

Activities

• Use the ps and kill commands to remove any defunct processes from the process table.
• Demonstration of various resource bottlenecks: memory, processes, disk, io.
• Configure syslog.conf to log emergency kernel messages.
• Write a cron file to search the /dev directory for data files.

System Monitoring

1. System Monitoring
   • Process Management
   • uptime
     • Can be used as indication of systematic degredation
   • ps
     • Provides snapshot of all system processes
   • top
     • Interaction version of ps with additional summary info
   • vmstat
     • Provides snapshot of overall memory
   
   
2. Monitoring CPU Utilization and Controlling Processes
   • nice and renice
     • Gives and changes runtime priority
   • kill and killall
     • Sends signals to processes, usually terminating them
   • Checking top for Zombies
     • Processes that have exited without parents noticing
     • Cannot be terminated with kill
   • nohup
     • Runs given command in the background
   • Memory Leaks
   
   
3. Checking and Evaluating Log Files
   • Kernel abd System Boot Messages
   • Log File Locations
     • /var/log directory
     • /etc/syslog.conf
       • The Selector Field
       • The Action Field
       • Security concerns
   
   
4. Scheduling Batch (cron) Jobs
   • cron - Scheduling Program that executes tasks at a given time
   • crontab - a program that submits tasks to the cron daemon
     • crontab filename - installs your cron file
     • crontab -l - displays your current cron file
     • crontab -r - removes your current cron file
     • crontab -u user - sets a cron job for another user
   • Crontab service can be denied or allowed on a per/user basis
   • crond cron daemon examines crontab files and at command files.

Relevant Commands and Files