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Troubleshooting and performance monitoring

Troubleshooting and performance monitoring. Unit objectives Identify good troubleshooting practices and troubleshoot common hardware and software problems Monitor system performance using command line and graphical utilities. Topic A: Troubleshooting. The maintenance cycle.

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Troubleshooting and performance monitoring

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  1. Troubleshooting and performance monitoring Unit objectives • Identify good troubleshooting practices and troubleshoot common hardware and software problems • Monitor system performance using command line and graphical utilities

  2. Topic A: Troubleshooting

  3. The maintenance cycle

  4. Troubleshooting methodology • Monitoring • Examine log files • Use monitoring utilities • Proactive maintenance • Prevent problems from occurring • Reactive maintenance • Fix problems when they occur • Troubleshooting procedures

  5. Troubleshooting a problem • Do similar systems hav problem • Examin system logs • View contents of proc directory • Run information gathering utilities • Research symptoms • Implement and test solutions • Document results and fix

  6. Common troubleshooting procedure

  7. Troubleshooting methodology: rules • Prioritize problems • According to severity • Spend a reasonable amount of time given priority • Try to solve the root of the problem • Avoid missing the underlying cause of a problem • Try to justify why a certain solution is successful

  8. Hardware problems • Conflicts • IRQ • Check dmesg, boot.log, messages • Check legacy vs. PnP • Absence of a device driver • Prevents operating system from using hardware devices • Kudzu program • Program used to detect and install support for new hardware

  9. The kudzu welcome screen

  10. Configuring hardware using kudzu

  11. Hardware failure • Hard Drives • Power down • Replace HD • Boot • Use fdisk to partition • Use mkfs to create filesystems • Restore data from backup • Use fstab to mount at startup

  12. Software problems • Dependencies • Prerequisites for program execution • shared libraries • other packages • rpm -V • ldd command • Displays shared libraries used by a program continued

  13. Software problems, continued • ldconfig command • Updates the /etc/ld.so.conf and /etc/ld.so.cache files • /etc/ld.so.conf files • Contains a list of directories that contain shared libraries • /etc/ld.so.cache file • Contains the location of shared library files

  14. Multimedia • Programs need codecs • Typically a shared library • If manually installed • Copy files to location • Update /etc/ld.so.conf and /etc/ld.so.cache

  15. File descriptorsand logs • Filehandles • Connections a program makes to files • ulimit command • Modifies process limit parameters • /var/log directory • Contains most system log files

  16. Operating system problems • Most software problems are related to the operating system • Typically problems • boot loaders • Filesystems • serial devices

  17. Operating system problems • Boot loaders • LILO • Linear command • No compacty • GRUB • Missing files • Make sure kernel is before 1024 cyliner • Turn on lba32 • Create bootdisk • mkbootdisk command

  18. Filesystem problems • fsck • unmont filesystem • Run fsck –f • If fsck can’t fix • Run mkfs • Restore data

  19. Keywords used with the setserial utility • Serial ports • Need to reset from defaults

  20. Topic B: Performance monitoring

  21. Performance monitoring • Hardware problems • Improper configuration • Old and failing • Jabbering • Failing hardware components send large amounts of information to the CPU continued

  22. Improving software performance • Upgrade CPU • Buss Mastering • More RAM • Faster hard drive • CD-ROM on separate controller • Smaller kernel

  23. sysstat utilities • System Statistics (sysstat) package • Performance monitoring utilities • mpstat, iostat, sar, and isag • Multiple Processor Statistics (mpstat) utility • Displays CPU statistics continued

  24. sysstat utilities, continued • Input/Output Statistics (iostat) command • Displays Input/Output statistics for block devices • System Activity Reporter (sar) command • Displays various system statistics

  25. Options to the sar command

  26. Options to the sar command

  27. Other performance monitoring utilities • top command • Displays memory usage, swap usage, average CPU Load • free command • Displays memory and swap statistics • vmstat command • Displays memory, CPU, and swap statistics

  28. Unit summary • Identified good troubleshooting practices and learned how to troubleshoot common hardware and software problems • Monitored system performance using utilities

  29. The system administrator wishes to view vmstat output once every 10 seconds for the next minute. Which of the following commands accomplishes this? A. vmstat 10 6 B. vmstat ­10 ­1min C. vmstat 10; sleep 60 D. vmstat ­­time='1 min' 10

  30. The system administrator wishes to view vmstat output once every 10 seconds for the next minute. Which of the following commands accomplishes this? A. vmstat 10 6 B. vmstat ­10 ­1min C. vmstat 10; sleep 60 D. vmstat ­­time='1 min' 10 Answer: A

  31. If a user wishes to monitor the last three lines of the log file messages.log and update it every 15 seconds, which of the following commands should be issued? A. sar ­f ­s 15 ­n 3 messages.log B. tail ­f ­s 15 ­n 3 messages.log C. watch ­f ­s 15 ­n 3 messages.log D. follow ­f ­s 15 ­n 3 messages.log

  32. If a user wishes to monitor the last three lines of the log file messages.log and update it every 15 seconds, which of the following commands should be issued? A. sar ­f ­s 15 ­n 3 messages.log B. tail ­f ­s 15 ­n 3 messages.log C. watch ­f ­s 15 ­n 3 messages.log D. follow ­f ­s 15 ­n 3 messages.log Answer: B

  33. Which of the following is the BEST tool to measure system performance baseline over a period of time? A. sar B. var C. pmap D. netstat

  34. Which of the following is the BEST tool to measure system performance baseline over a period of time? A. sar B. var C. pmap D. netstat Answer: A

  35. A new RPM package returns a large number of errors and has never run successfully. Which of the following commands should be run as a FIRST step to troubleshooting this problem? A. verify <package_name> B. rpm ­V <package_name> C. rpmdb ­v <installation_file> D. diff ­­rpm <package_name> <installation_file>

  36. A new RPM package returns a large number of errors and has never run successfully. Which of the following commands should be run as a FIRST step to troubleshooting this problem? A. verify <package_name> B. rpm ­V <package_name> C. rpmdb ­v <installation_file> D. diff ­­rpm <package_name> <installation_file> Answer: B

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