Implement a Disaster Recovery Cluster Using MariaDB Galera Cluster and Galera Load Balancer

In this activity, you are working as a DBA and have been tasked with setting up a MariaDB Galera Cluster in a Disaster Recovery configuration.

A POC (proof of concept) cluster has been started for you to configure.
You will need to install the Galera Load Balancer and configure it appropriately.

Learning Objectives

Successfully complete this lab by achieving the following learning objectives:

Set the root Database User’s Password and Create a Database User Account

The database nodes are running and connected to the cluster, however the root user’s password has not been set.
You must first set the root user’s password by running the mysql_secure_installation script:

sudo mysql_secure_installation

Now you can connect to the database as the root user and create a user account:

mysql -u root -p

Once connected, you can use the following SQL to create a user named remote who is able to log in remotely. Be sure to replace mypasswd with a password of your choice:

create user remote identified by 'mypasswd';
grant usage on *.* to 'remote'@'%' identified by 'mypasswd';

Install the Prerequisite Packages

sudo yum -y install git autoconf automake libtool gcc-c++ nmap-ncat

Build the Binaries

git clone https://github.com/codership/glb
cd glb
./bootstrap.sh
./configure
make
sudo make install

Configure and Start Galera Load Balancer

The primary node will have a weight of 10. Adding the DR site with a lower weight provides automatic failover should the primary node fail.
Using the --single option causes all connections to go to a single server with the highest weight of those available:

sudo cp /home/cloud_user/glb/files/mysql.sh /usr/local/bin/mysql-check.sh
sudo cp /home/cloud_user/glb/files/glbd.sh /etc/init.d/glb

sudo vim /etc/sysconfig/glbd

# Address to listen for client connections at. Mandatory parameter.
# To bind to all interfaces only port should be specified.
LISTEN_ADDR="10.0.1.100:13306"

# Address for controlling connection. Mandatory part is port.
# If not specified control socket will not be opened
CONTROL_ADDR="127.0.0.1:4444"

# Target servers for client connections, space separated.
# Target specification: IP[:PORT[:WEIGHT]] (WEIGHT and PORT optional)
# WEIGHT defaults to 1, PORT defaults to LISTEN_ADDR port.
DEFAULT_TARGETS="10.0.1.100:3306:10 10.0.1.110:3306:1"

# Other glbd options if any as they would appear on the command line.
OTHER_OPTIONS="--single --watchdog exec:'/usr/local/bin/mysql-check.sh -uremote -pmypasswd'"

Start the service:

sudo service glb start
sudo service glb status

Confirm Connections to Primary

Connect to the load balancer:

mysql -h 10.0.1.100 -P 13306 -u remote -p

The connection is sent to the single server with the highest weight of those available, in this case node0:

sudo service glb status

Failover to DR Site

A manual failover can be triggered by changing the weight of the node:

service glb add 10.0.1.100:3306:1
service glb add 10.0.1.110:3306:10

A failure of node1 can be simulated by stopping the mariadb service:

sudo systemctl stop mariadb.service

Connections will now be routed to the DR site automatically.

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Implement a Disaster Recovery Cluster Using MariaDB Galera Cluster and Galera Load Balancer

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