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How to setup Linux loadbalancer using: LVS + ldirectord + heartbeat 2 on CentOS

Steps to setup heartbeat-2.1.4 on centos 5.2.

In this document you will find procedure how to setup lb01 and lb02 as loadbalancer for 2 or more web servers. In this example I have used only 2 webservers i.e web01 and web02. In total there are 4 virtual servers. All four servers are virtual servers. I am using Xen as dom0. 

After installing base operating system (I have installed CentOS 5.2) we need to install following packages on both loadbalancer linux boxes. As heartbeat is not available with standard packages you will need to download it.

How to convert / migrate image based vm (guest / dom-U) to LVM based vm (virtual machine)-(Guest / dom-U) using xen.

Hi all, In this article we will learn how to install virtual machine on sparse file (image file) and how to migrate / move it to LVM based storage / disk. It is recommended to use LVM based partition to install virtual machines for productions environment, as you may experience performance issues if you use images (sparse files) to install virtual machine.

How to install virtual machine on image based disk ...

Increase max_connections in mysql without restarting mysqld service.

By default in mysql database server max_connections is set to 100. This value indicates how many maximum concurrent connections mysql server can handle. If mysql reaches to it maximum (max) limit then you can see errors like "too many connections". I assume that you have enough hardware resources (Mainly RAM )to handle more connections, here with this article I will share a TIP to increase max_connections in mysql.

As we know my.cnf is default configuration file for mysqld service and by default it is located in /etc directory unless and until you have changed it.

How to install and configure AMAND backup server and client on LINUX

Hi all, In this article we will learn how to install amanda backup server and cofigure it to start taking backups. It is completely free and based on GPL License. we don't need to pay any license fee to use this software in live/production environment.

Steps to install amanda backup server.

  1. Install centos 5.2 x86_64.
  2. Get rpm from www.amanda.org/download.php for latest stable version of amanda server. E.g amanda-backup_server-2.6.1p2-1.rhel5.x86_64.rpm
  3. install this downloaded rpm using #rpm –ivh command

PostgreSQL Cheat Sheet

PostgreSQL Cheat Sheet

CREATE DATABASE

CREATE DATABASE dbName;

CREATE TABLE (with auto numbering integer id)

CREATE TABLE tableName (
 id serial PRIMARY KEY,
 name varchar(50) UNIQUE NOT NULL,
 dateCreated timestamp DEFAULT current_timestamp
);

Add a primary key

ALTER TABLE tableName ADD PRIMARY KEY (id);

Create an INDEX

CREATE UNIQUE INDEX indexName ON tableName (columnNames);

How to setup linux loadbalancer for windows real server using ldirectord-lvs-heartbeat

Required operating system and packages

First of all install centos 5.2 with minimal packages and no gui required.
Packages required for setting up linux server as loadbalancer are as below.
heartbeat-2.1.4-4.1.i386.rpm
heartbeat-devel-2.1.4-4.1.i386.rpm
heartbeat-ldirectord-2.1.4-4.1.i386.rpm
heartbeat-pils-2.1.4-4.1.i386.rpm
heartbeat-stonith-2.1.4-4.1.i386.rpm
libnet-1.1.2.1-2.1.i386.rpm
perl-MailTools-1.76-1.el5.rf.noarch.rpm

There might me some more package dependencies but it can be resolved by installing those packages from cd.

How to compile Berkeley DB and OpenLDAP on linux

Hi,
Many times we need to install packages which are available only in form of source code. Or sometimes we need to install couple of different versions of packages on same server... what ever reason it may be, We can achieve this by compiling packages.

Here in this article I will just show you quick steps how to compile berkeley db and openldap.

First of all we need to download Berkeley DB and OpenLDAP. use following links to download latest stable versions.

To download Berkeley DB
http://www.oracle.com/technology/software/products/berkeley-db/index.htm...

How to change date and time in linux

Today I wanted to change date and time on one of my server quickly from command line. I am aware with command line options but every time I want to do it, I need to read man page or help to get perfect combination so i decided to write this small how to which can help me and you every time we want to change date and time in linux from command line.

Remember, CLI (command line interface) is most powerful for users / administrators like us.

To change system date in linux, type:-

#date MMDDhhmmYYYY.ss

Postgresql: show tables, show databases, show columns

Hi all, In this article you will know some very very basic commands about postgresql. When i started learning postgresql, I found bit strange when "show databases", "show tables", and "show columns" command did not work. I was using mysql and I am still using mysql but it is just matter of learning one more database as postgresql started becomming popular now. So.. If you have question in your mind how to list databases, tables and colums in postgresql database then I have answer for you.

First of all to connect to postgresql you need to use :

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