Diagnostics of a Linux System
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This document provides an overview of the basic parts of a Linux system, including the boot loader, kernel, glibc, and init processes. It also covers methods for analyzing and debugging applications, running services, and troubleshooting server issues. Key tools discussed include strace, ltrace, and information about memory and storage management.
Diagnostics of a Linux System
- 1. Diagnostics of a Linux System Understanding Your Operating System Stephan Barth Sander van Vugt Senior Technical Support Engineer Independent Trainer and Consultant stephan.barth@novell.com mail@sandervanvugt.nl
- 2. Overview A Few Words About Us Basic Parts of a Linux System (theory) Analyzing and Debugging Other Important Tools and Commands Demo: Troubleshooting Server Issues 2 © Novell, Inc. All rights reserved.
- 3. Basic Parts of a Linux System
- 4. Basic Parts of a Linux System Boot loader, e.g. Grub, LILO Kernel glibc init 4 © Novell, Inc. All rights reserved.
- 5. Basic Parts of a Linux System • Monolithic kernel with modules • Compiled in options and drivers – zcat /proc/config.gz • Modules that are being loaded – lsmod – dmesg – /proc and /sys 5 © Novell, Inc. All rights reserved.
- 6. Basic Parts of a Linux System • Glibc – # /lib/libc.so.6 – /etc/ld.so.conf – /etc/ld.so.cache – ldconfig – Timezone – rpm -q --provides glibc – ldd and nm – More info with: info glibc • Try to compile packages on your own 6 © Novell, Inc. All rights reserved.
- 7. Basic Parts of a Linux System • init • ldd /sbin/init • /etc/inittab – initial boot – runlevels – tty's Demo 7 © Novell, Inc. All rights reserved.
- 8. Understanding Your Operating System • What happens during boot? – Kernel start up and initrd – boot options – boot.msg > Examples – module options – debug kernel – MCE – hal – lspci, lsusb 8 © Novell, Inc. All rights reserved.
- 9. Understanding Kernel Loading from GRUB • GRUB is the first thing that runs when booting the server • Responsible for loading kernel and initrd • root file system is activated as a kernel argument • Specific options can be loaded from the boot prompt Demo 9 © Novell, Inc. All rights reserved.
- 11. Application Debugging • ldd $(which gpg) • rpm -q --requires gpg2 • strace / ltrace • objdump • GNU debugger gdb • Valgrind • Closed source software 11 © Novell, Inc. All rights reserved.
- 12. Running Services strace/ltrace Increase debug level Change init script – very last option 12 © Novell, Inc. All rights reserved.
- 13. Memory and Storage • Memory debugging is difficult – ps – top – sar • Disk usage – df vs. du 13 © Novell, Inc. All rights reserved.
- 14. Other Important Tools and Commands
- 15. Miscellaneous Tools • Parted • Ethtool • RPM – rpm -qf – rpm -qa --last – zypper • How to find files, packages: ARCHIVES.gz, pin, distpin 15 © Novell, Inc. All rights reserved.
- 16. Looking at Startup • Different stages in startup – GRUB – loading of kernel and initrd – init taking over and doing initial boot – init starting runlevels Demo 16 © Novell, Inc. All rights reserved.
- 17. Novell Tools ® supportconfig Novell Support Advisor 17 © Novell, Inc. All rights reserved.
- 18. Demo: Troubleshooting Server Issues
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