Replicación es la copia sincronizada entre dos o más servidores de bases de datos, de forma de que cualquiera de ellos puede entregar los mismos resultados a sus clientes. Se basa en un esquema «maestro-esclavos», en el que el maestro mantiene la base de datos original y los esclavos las copias.
El funcionamiento es el siguiente: los servidores esclavos se conectan al maestro para consultar sus logs y asg mantenerse informados de las operaciones de modificación que ha realizado (insert, delete, update, …) para a su vez poder realizarlas también ellos y mantener una replica exacta de la base de datos del servidor maestro. Los servidores esclavos sólo sirven para consultas.
Esto nos proporciona:
Replica automática de los datos en máquinas remotas.
Balanceo de la carga (de las consultas).
Alta disponibilidad mediante redundancia de servidores.
Si cae el maestro
Copias de seguridad en esclavos sin interrumpir maestro.
Hack Proofing Linux:A Guide to Open Source Security is designed to help you deploy a Linux system on the Internet in a variety of security roles.This book provides practical instructions and pointers concerning the open source security tools that we use every day. First, we show you how to obtain the software; and then, how to use the Bastille application to harden your Linux operating system so that it can function securely as it fulfills a specific role of your choice (e.g., as a Web server, as an E-mail server, and so forth).You will also learn how to use your Linux system as an auditing tool to scan systems for vulnerabilities as well as create an Intrusion Detection System (IDS), which enables your Linux system to log and respond to suspicious activity. From virus protection to encrypting transmissions using Gnu Privacy Guard and FreeSWAN, you will be able to con?gure your system to secure local data as well as data that will be passed along the network.After reading this book, you will be able to identify open source and for-fee tools that can help you further secure your Linux system. We have also included chapters concerning ways to sniff and troubleshoot network connections and how to implement strong authentication using One Time Passwords (OTP) and Kerberos.Tools such as Squid proxy server and Ipchains/Iptables will help you use your Linux system so that it can act as a firewall.With the tools on the accompanying CD as well as the advice and instructions given in this book, you will be able to deploy your Linux system in various roles with confidence. We decided to focus on pro?ling the most commonly used security tools found on the Linux platform.We also decided to emphasize the real-world implementation of these tools, as opposed to just providing conceptual overviews. Finally, we decided to describe the steps you should take when things go wrong.As a result, we have created a book that is a valuable resource that helps you use your Linux system as efficiently as possible