Appendix A. Troubleshooting
A.1. Debugging and Troubleshooting Tools
kvm_stat- Retrieves KVM runtime statistics. For more information, see Section A.4, “kvm_stat”.
ftrace- Traces kernel events. For more information, see the What is ftrace and how do I use it? solution article (subscription required).
vmstat- Displays virtual memory statistics. For more information, use the
iostat- Provides I/O load statistics. For more information, see the Red Hat Enterprise Linux Performance Tuning Guide
lsof- Lists open files. For more information, use the
systemtap- A scripting utility for monitoring the operating system. For more information, see the Red Hat Enterprise Linux Developer Guide.
crash- Analyzes kernel crash dump data or a live system. For more information, see the Red Hat Enterprise Linux Kernel Crash Dump Guide.
sysrq- A key combination that the kernel responds to even if the console is unresponsive. For more information, see the Red Hat Knowledge Base.
ip route, and
tcpdump- diagnoses packet traffic on a network. This command is useful for finding network abnormalities and problems with network authentication. There is a graphical version of
brctl- A networking utility that inspects and configures the Ethernet bridge configuration in the Linux kernel. For example:
brctl showbridge-name bridge-id STP enabled interfaces ----------------------------------------------------------------------------- virtbr0 8000.feffffff yes eth0 $
brctl showmacs virtbr0port-no mac-addr local? aging timer 1 fe:ff:ff:ff:ff: yes 0.00 2 fe:ff:ff:fe:ff: yes 0.00 $
brctl showstp virtbr0virtbr0 bridge-id 8000.fefffffffff designated-root 8000.fefffffffff root-port 0 path-cost 0 max-age 20.00 bridge-max-age 20.00 hello-time 2.00 bridge-hello-time 2.00 forward-delay 0.00 bridge-forward-delay 0.00 aging-time 300.01 hello-timer 1.43 tcn-timer 0.00 topology-change-timer 0.00 gc-timer 0.02
- strace is a command which traces system calls and events received and used by another process.
- vncviewer connects to a VNC server running on your server or a virtual machine. Install vncviewer using the
yum install tigervnccommand.
- vncserver starts a remote desktop on your server. Gives you the ability to run graphical user interfaces, such as virt-manager, using a remote session. Install vncserver using the
yum install tigervnc-servercommand.