debug pacemaker cluster easily

Debugging pacemaker cluster through logs will be much more easier post reading this article. This would help you in either troubleshooting or root cause analysis. It does not need any additional tools except your attention. Have reproduced and collected logs from various scenario to present here as example. I used SUSE 11 with HAE system for testing.

The first thing to do is look in system log for the terms ERROR and WARN.

#grep -e ERROR -e WARN /var/log/messages

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How to use SUDO Runas alias?

Usually SUDO used by non-superuser to run command with root privileges. But in few scenario application/commands stick with it native user. Even with root user privileges it won’t work as expected. For example to run any oracle commands you need to be oracle user.

Here consider mission critical application “xapp1” and it uses user “app1”. Allowing others to login as app1 will result in trouble. The secure way is to allow user to execute limited commands as app1 user.

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Easy way to open Linux X-Term in Windows

Using Xming & Putty can connect to remote Linux X-server from windows desktop. By this way you will be able to view remote server GUI from windows desktop. This avoids need of physical console access to server.

Because granting server console access to application or normal user is a bad idea. One of my user pressed Ctr+Alt+Del while working on VMware virtual machine console. Which made system to reboot.

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SUDO Command Alias

Usage of sudo command alias and it various useful features with examples given.

Syntax

                Cmnd_Alias        NAME   =   cmnd1, cmnd2, cmnd3 ….

To define command alias in sudoers file must remember two hard coded rules

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Pacemaker Corosync Cluster Overview

How does Pacemaker Corosync cluster operates? What is the relation between pacemaker and corosync? The functionality and concept overview has been explained here. SUSE Linux high availability and Redhat high availability using pacemaker corosync cluster majorly. Still many other flavors such as Ubuntu, Debian are using pacemaker with corosync as their high availability solution.

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Linux library files

What is lib files in Linux?
A library(lib) is a file containing compiled code from various object files stuffed into a single file. It may contain a group of functions that are used in a particular context. For example, the ‘pthread’ library is used when thread related functions are to be used in the program.

Broadly, a library (or Program Library) can be of two types :

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