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Articles taggués ‘cluster’

MySQL Master / Slave Replication

29/01/2016 Comments off

Source: Uptime Made Easy

Master Slave MySQL Replication Summary

Master / Slave replication in MySQL is a great way to store an exact replica of your database on another machine in another location as part of a disaster recovery plan.  Before setting up Master / Slave replication there are a few things to remember.

  • Writes – Writes to the master database should make it to the slave.  But writes to the slave will not make it to the master.  If you do write records to the slave database directly, be prepared to have to either recreate the records or back them up separately and recover them if the replication breaks.  Many times the only way to get the databases to replicate again is to backup the master and recover it over the top of the slave deleting anything that was in the slave database before.
  • Broken Replication – Writes made directly to the slave can cause the replication to break due to duplicate key rows, etc..  Always write to the master.
  • Reads – Reads should be possible from either server.  Many organizations will use replication so as to create another database to read from thereby taking the load of all of their select statements and reports off the master server.

 

MySQL Replication schemeMaster Slave MySQL Replication

Steps to Setup MySQL Master / Slave Replication

Prerequisites

We will be assuming that the following prerequisites are done prior to beginning the steps listed below:

  • MySQL has been installed on both the master and the slave servers
  • The slave server is able to communicate directly to the mysqld port (typically 3306) on the master server, meaning that there is no firewall, routing, NAT or other problems preventing communication.
  • You have an administrator MySQL user that can create users on both the master and the slave machines.
  • You have permissions to edit the /etc/my.cnf files on both machines and enough privileges to restart mysql.

That should be it!  Let’s begin setting it up.

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MySQL – Migrate Users from Server to Server

29/01/2016 Comments off

mysql migrate usersSometimes we need to migrate our databases to a new MySQL server.  It is easy to move the databases, but without the users and their permissions, our new databases would be worthless.  Below is a step-by-step on migrating MySQL users to a new MySQL server

Step 1 – Create a Query List That We Can Use to Get Grants for All Users

I use these options so that I wouldn’t get any formatting characters that I would have to manually delete later.

  • -N skip column names in the output
  • -p password – Asks me to type the password so nobody can get it from the command line history
  • -s  silent mode – less formatting output that we don’t want like “|” and “-“

So, let’s get a list of the users in a query that we can use to get the grants.  Our query will be output into the “myfile” file

$ mysql -uroot -N -p -s > myfile
Enter password:
select Distinct CONCAT(‘show grants for `’, user, ‘`@`’, host, ‘`;’) as query from mysql.user;
quit

If we want to see what our query file look like, we can take a quick peek:

[root@classes-dev-mysql ~]# cat myfile
show grants for `user1`@`%`;
show grants for `user2`@`%`;
show grants for `user3`@`10.%`;
show grants for `user4`@`10.%`;
show grants for `jeff`@`10.%`;

Step 2 – Create the MySQL Grant File

We don’t have quite what we want and need yet.  We are looking for a query that will create all of our users on the new MySQL server.  We need to run the query that we just created and it will give us the query that we will use later to create the users.  It will create our grant permission statements in a file named “grantfile

[root@classes-dev-mysql ~]# mysql -uroot -N -p -s -r < myfile > grantfile
Enter password:

We can take a peek at what our grantfile contains:

$ cat grantfile
GRANT USAGE ON *.* TO ‘user1’@’%’ IDENTIFIED BY PASSWORD ‘5ea9af6g6t27032f’
GRANT ALL PRIVILEGES ON `database1`.* TO ‘user1’@’%’
GRANT USAGE ON *.* TO ‘user2’@’10.%’ IDENTIFIED BY PASSWORD ‘2a123b405cbfe27d’
GRANT SELECT ON `database1`.`table1` TO ‘user2’@’10.%’GRANT ALL PRIVILEGES ON *.* TO ‘user3’@’10.%’ IDENTIFIED BY PASSWORD ‘753af2za1be637ea’
GRANT SELECT, INSERT, UPDATE, DELETE ON *.* TO ‘user3’@’10.%’ IDENTIFIED BY PASSWORD ’08ad9be605rfgcb’…

Step 3 – Create Users and Grant MySQL Permissions on the New MySQL Machine

Now we are done working on the source machine.  We need to copy our file named “grantfile” over to the new machine.

$ scp grantfile myuser@mysql2.uptimemadeeasy.com:/home/myuser

Next, we login to the destination or the new MySQL machine that we are building and run the “grantfile” in MySQL to create our users on the new MySQL machine.

$ mysql -uroot -p < ./grantfile

That’s it.  As long as our databases are named the same in the new MySQL, our users should be ready to use the copy of the databases in the new MySQL machine.

Source: Uptime Made Easy

Installing A High Availability Web Server Cluster On Ubuntu 12.10 Using HAProxy, HeartBeat And Lampp

05/11/2015 Comments off

What is the main objective of this entire topology?

high availability web server clusterRedundancy and Load Sharing! Imagine a scenario where your single web server is receiving millions and millions of HTTP requests per second, the CPU load is going insane, as well as the memory usage, when suddenly “crash!”, the server dies without saying good-bye (probably because of some weird hardware out-stage that you certainly won’t have time to debug). Well, this simple scheme might lead you into a brand new world of possibilities

What is this going to solve?

Hardware Failures! We are going to have redundant hardware all over the place, if one goes down, another one will be immediately ready for taking its place. Also, by using load sharing schemes, this is going to solve our High Usage! issue. Balancing the load among every server on our “farm” will reduce the amount of HTTP request per server (but you already figured that out, right?).
Let’s set it up! Firstly, we’re not going to use a domain scheme (let’s keep it simple), make sure your /etc/hosts file looks exactly like the picture below on every machine:
#vi /etc/hosts
192.168.0.241   haproxy
192.168.0.39 Node1
192.168.0.30 Node2
192.168.223.147 Node1
192.168.223.148 Node2
192.168.0.58 Web1
192.168.0.139 Web2
192.168.0.132 Mysql

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Installing a high availability web server cluster on Ubuntu 12.04 LTS using HAProxy, HeartBeat and Nginx

05/11/2015 Comments off

How to set-up a high-availability cluster

Here are a few notes about how to set-up a high-availability web server farm using Ubuntu 12.04 LTS using a whole load of awesome software (HAProxy, HeartBeat, Watchdog and Nginx)

The setup

In my setup I have five virtual machines, these are named and used for the following:-

haproxy1 – Our first proxy (master)/load-balancer (running HAProxy, HeartBeat and Watchdog) [IP address: 172.25.87.190]
haproxy2 – Our second proxy (failover)/load-balancer (running HAProxy, HeartBeat and Watchdog) [IP address: 172.25.87.191]
web1 – Our first web server node (running nginx) [IP address: 172.25.87.192]
web2 – Our second web server node (running nginx) [IP address: 172.25.87.193]
web3 – Our third web server node (running nginx) [IP address: 172.25.87.194]

The servers are connected in the following way:-

thesetup

In my next post I will also explain how to configure the web servers to point to a backend shared storage cluster (using NFS) and a MySQL cluster server to have a truly highly available web hosting platform.

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How To Create a High Availability Setup with Heartbeat and Floating IPs on Ubuntu 14.04

28/10/2015 Comments off

Source: Digital Ocean – Mitchell Anicas

Introduction

Heartbeat is an open source program that provides cluster infrastructure capabilities—cluster membership and messaging—to client servers, which is a critical component in a high availability (HA) server infrastructure. Heartbeat is typically used in conjunction with a cluster resource manager (CRM), such as Pacemaker, to achieve a complete HA setup. However, in this tutorial, we will demonstrate how to create a 2-node HA server setup by simply using Heartbeat and a DigitalOcean Floating IP.

If you are looking to create a more robust HA setup, look into using Corosync and Pacemaker or Keepalived.

Goal

When completed, the HA setup will consist of two Ubuntu 14.04 servers in an active/passive configuration. This will be accomplished by pointing a Floating IP, which is how your users will access your services or website, to point to the primary, or active, server unless a failure is detected. In the event that the Heartbeat service detects that the primary server is unavailable, the secondary server will automatically run a script to reassign the Floating IP to itself via the DigitalOcean API. Thus, subsequent network traffic to the Floating IP will be directed to your secondary server, which will act as the active server until the primary server becomes available again (at which point, the primary server will reassign the Floating IP to itself).

ha-diagram-animated

Note: This tutorial only covers setting up active/passive high availability at the gateway level. That is, it includes the Floating IP, and the load balancer servers—Primary and Secondary. Furthermore, for demonstration purposes, instead of configuring reverse-proxy load balancers on each server, we will simply configure them to respond with their respective hostname and public IP address.

To achieve this goal, we will follow these steps:

  • Create 2 Droplets that will receive traffic
  • Create Floating IP and assign it to one of the Droplets
  • Create DNS A record that points to Floating IP (optional)
  • Install Heartbeat on Droplets
  • Configure Heartbeat to Run Floating IP Reassignment Service
  • Create Floating IP Reassignment Service
  • Test failover

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MySQL Cluster Replication: Multi-Master and Circular Replication

28/10/2015 Comments off

mysql-multi-master-replication-14-638Beginning with MySQL 5.1.18, it is possible to use MySQL Cluster in multi-master replication, including circular replication between a number of MySQL Clusters.

Prior to MySQL 5.1.18, multi-master replication including circular replication was not supported with MySQL Cluster replication. This was because log events created in a particular MySQL Cluster were wrongly tagged with the server ID of the master rather than the server ID of the originating server.

Circular replication example. In the next few paragraphs we consider the example of a replication setup involving three MySQL Clusters numbered 1, 2, and 3, in which Cluster 1 acts as the replication master for Cluster 2, Cluster 2 acts as the master for Cluster 3, and Cluster 3 acts as the master for Cluster 1. Each cluster has two SQL nodes, with SQL nodes A and B belonging to Cluster 1, SQL nodes C and D belonging to Cluster 2, and SQL nodes E and F belonging to Cluster 3.

Circular replication using these clusters is supported as long as the following conditions are met:

  • The SQL nodes on all masters and slaves are the same
  • All SQL nodes acting as replication masters and slaves are started using the --log-slave-updates option

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Simple failover cluster using UCARP on Ubuntu

09/10/2015 Comments off

In this tutorial, I’ll show you the steps to create a simple failover cluster on Ubuntu using CARP. To make the things meaningful,we’ll create the cluster for Apache service but you can use it for any other service, which relay on IP.

Scenario:

Here is my Setup:

PrimarySrv: This is the main server, where I configured the apache and which act as Master (IP: 192.168.1.202)
SecondarySrv: 2nd Apache Server where I configured the apache exactly like on PrimarySrv (IP : 192.168.1.203)
192.168.1.250 : Virtual IP address,created using Ucarp.

Ucarp is really simple, it works like this,when the PrimarySrv is up,it will assign the virtual IP 192.168.1.250 to it, in case that PrimarySrv is down then it will assign virtual IP to the SeconadrySrv and when the PrimarySrv will come online, it will assign the virtual IP once again to it.

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Un cluster DRBD / MySQL avec Heartbeat sur Debian 7

16/09/2015 Comments off

Source: denisrosenkranz.com

Nous avons vu précédement comment mettre un place un Cluster Apache actif/passif avec DRBD et HeartBeat. Dans ce tutoriel nous allons voir comment faire la même chose mais avec MySQL.

La configuration de DRBD et de Heartbeat est la même que pour le tutoriel précédent.

Voilà ce que nous allons mettre en place

DRBDMySQL

Donc pour faire ce tutoriel suivez le tutoriel suivant jusqu’a « Installation d’apache« :

Un cluster DRBD/Apache avec Heartbeat sur Debian 7

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Un cluster DRBD / Apache avec Heartbeat sur Debian 7

16/09/2015 Comments off

C’est quoi Heartbeat?

drbd apache debianHeartbeat est un logiciel de surveillance de la disponibilité des programmes, pour les systèmes d’exploitation Linux, FreeBSD, OpenBSD, Solaris et MacOS X. Il est distribué sous licence GPL.

Heartbeat écoute les battements de cœur – des signaux émis par les services d’une grappe de serveurs lorsqu’ils sont opérationnels. Lorsque qu’un serveur devient défaillant, Heartbeat le detecte (puisqu’il n’entend plus ses battements de coeurs) et bascule les services surveillés sur un autre serveur. Pour que cela soit transparent pour les utilisateurs, Heartbeat met en place une IP virtuelle unique qui est balancée entre les deux serveurs.

Voici ce que nous allons mettre en place

Schéma

Mise en place de la solution

Pour ce tuto, nous allons partir du Cluster DRBD que nous avons mis en place dans le tutoriel précédent:

DRDB sur Debian 6

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DRBD sur Debian 6

16/09/2015 Comments off

Source: denisrosenkranz.com

Qu’est-ce que DRBD?

DRBD pour Distributed Replicated Block Device est comparable à un RAID 1 mais en réseau, c’est à dire que deux disques, partitions ou même un LVM peuvent être repliqué d’un disque à un autre via un réseau ethernet ou fibre optique.
Cela permet donc d’assurer la disponibilité de vos données en cas de crash complet d’une machine. Ce que ne permet pas de faire un RAID classique.

DRBDDiag

Pour ce tuto nous allons donc utiliser deux machines virtuelles sous Debian 6.

Lire la suite…

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