Linux+ Unit 15

Course ILT

Troubleshooting and performance monitoring

Unit objectives  Identify good troubleshooting practices, and troubleshoot common hardware and software-related problems  Monitor system performance by using command-line and graphical utilities  Understand the purpose and usage of kernel modules  Troubleshoot and tune the hard disk

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Topic A    

Topic A: Troubleshooting Topic B: Performance monitoring Topic C: Customizing the kernel Topic D: Troubleshooting and tuning the hard disk

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The maintenance cycle

Troubleshooting methodology Course ILT

 Monitoring – Examine log files – Use monitoring utilities

 Proactive maintenance – Prevent problems from occurring

 Reactive maintenance – Fix problems when they occur

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Common troubleshooting procedures

Troubleshooting methodology: Rules

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 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

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Activity A-1

Discussing troubleshooting methodology

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The KDE Control Center

Hardware-related problems Course ILT

 Absence of a device driver – Prevents operating system from using hardware devices

 Kudzu program – Program used to detect and install support for new hardware

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The kudzu welcome screen

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Configuring hardware using kudzu

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Activity A-2

Resolving hardware problems

Software-related problems Course ILT

 Dependencies – Prerequisites for program execution  Shared libraries  Other packages

 ldd command – Displays shared libraries used by a program

continued

Software-related problems, continued

Course ILT

 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

File descriptors and logs Course ILT

 File descriptors – Connections a program makes to files

 unlimit command – Modifies process limit parameters

 /var/log directory – Contains most system log files

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OS-related problems  Most software problems are related to the operating system – Typically problems with boot loaders, filesystems, and serial devices

 mkbootdisk command – Creates a boot floppy disk

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Keywords used with the setserial utility

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Exercise A-3

Resolving software-related problems

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Activity A-4

Viewing and modifying package dependencies

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Topic B    

Topic A: Troubleshooting Topic B: Performance monitoring Topic C: Customizing the kernel Topic D: Troubleshooting and tuning the hard disk

Performance monitoring Course ILT

 Hardware problems – Improper configuration – Old and failing

 Jabbering – Failing hardware components send large amounts of information to the CPU

continued

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Improving software performance      

Upgrade CPU Bus mastering More RAM Faster hard drive CD-ROM on separate controller Smaller kernel

sysstat utilities Course ILT

 System Statistics (sysstat) package – Performance monitoring utilities – mpstat, iostat, sar, and isag

 Multiple Processor Statistics (mpstat) utility – Displays CPU statistics

continued

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sysstat utilities, continued  Input/Output Statistics (iostat) command – Displays input/output statistics for block devices

 System Activity Reporter (sar) command – Displays various system statistics

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Options for the sar command

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Monitoring performance: sysstat utilities

 Interactive System Activity Grapher (isag) command – Graphs system performance – Uses information stored in the /var/log/sa directory

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Choosing a file to view by using ISAG

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Choosing statistics by using ISAG

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Viewing user statistics by using ISAG

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Activity B-1

Using the mpstat, iostat, and sar commands

Other performance monitoring utilities

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 free command – Displays memory and swap statistics

 vmstat command – Displays memory, CPU, and swap statistics

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Activity B-2

Using the free and vmstat commands

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Topic C    

Topic A: Troubleshooting Topic B: Performance monitoring Topic C: Customizing the kernel Topic D: Troubleshooting and tuning the hard disk

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Device drivers and features  Many compiled into the kernel  May also be inserted into the kernel as modules – Reduces size of the kernel – Runs faster

 Compile standard device support into the kernel  Support for other devices and features as modules

Kernel modules Course ILT

 insmod command – Inserts a module into the kernel

 modprobe command – Inserts module and all necessary prerequisite modules into the kernel

 lsmod command – Lists modules currently used by the kernel

continued

Kernel modules, continued Course ILT

 rmmod command – Removes a module from the kernel

 /etc/modules.conf file – Used to load and alias modules at system initialization

 /etc/rc.d/rc.local file – Loads modules at system initialization

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Activity C-1

Managing kernel modules

Compiling a new Linux kernel Course ILT

 /usr/src/linux – Contains source code for the kernel during compilation

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The make menuconfig interface

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The make xconfig interface

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Configuring code maturity level options

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Configuring USB support

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Activity C-2

Compiling and using a new kernel

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Patching the Linux kernel  Applies only the updates needed to bring kernel to new level  Patch command – Used to apply a patch to the kernel source code

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Exercise C-3

Discussing kernel patches

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Topic D    

Topic A: Troubleshooting Topic B: Performance monitoring Topic C: Customizing the kernel Topic D: Troubleshooting and tuning the hard disk

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The hdparm program  Displays detailed information about hard disks  Runs simple tests of hard disk performance

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Activity D-1

Using the hdparm program

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The bonnie program  A hard disk benchmarking program  Checks the read and write speed of your hard disk

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Activity D-2

Tuning hard disk performance

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Unit summary  Identified good troubleshooting practices, and learned how to troubleshoot common hardware- and software-related problems  Monitored system performance by using command-line and graphical utilities  Understood the purpose and usage of kernel modules  Learned how to troubleshoot and tune the hard disk