Linux kernel remounts the filesystem into read-only mode whenever it cannot process I/O. This might happen due to various reasons such as disk failure, SAN connectivity issue, disk with bad blocks etc. On Virtual machine and SAN based storage environment even the high latency may lead to I/O hung and result in read-only mode.
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
Evolution of Intel Processor since 19th Century
Intel is the masterpiece in computer processor world. Intel Corporation founded on 18 July 1968. The most successful processors from Intel since 1993 are listed with rare unseen pictures. I do collected interesting unknown information about each processor. Hope you enjoy this post.
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.
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.
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
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.
Password quality check for OpenLDAP
Topic
1. Password quality check for OpenLDAP
2. Configure password quality check – Openldap
There is no standard OpenLDAP module for password quality check. How to make OpenLDAP server to check the strength and quality of password? How to reject the password which does not meet desired standards? There is an alternate solution available.
Network problem after kernel upgrade
Are you facing network problem after kernel upgrade? Does system Ethernet cards not visible post kernel upgrade? If your system falls under below categories, then this solution may fix your network issue.
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 :