- A Cloud Guru
Implement a Cluster to Reduce Client Read Latency Using MariaDB Galera Cluster and Galera Load Balancer
In this activity you are working as a DBA and have been tasked with configuring a MariaDB Galera Cluster to reduce client read latency. 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.
Table of Contents
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
rootuser's password has not been set. You must first set the
rootuser's password by running the
Now you can connect to the database as the
rootuser and create a user account:
mysql -u root -p
Once connected, you can use the following SQL to create a user named
remotewho 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
First copy the MySQL Watchdog script and Galera Load Balancer service files into place:
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
We will use the Source Tracking (
--source) policy to ensure that connections always go to the same node, reducing client latency:
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" # Other glbd options if any as they would appear on the command line. OTHER_OPTIONS="--source --watchdog exec:'/usr/local/bin/mysql-check.sh -uremote -pmypasswd'"
Start the service:
sudo service glb start sudo service glb status
mysql -h 10.0.1.100 -P 13306 -u remote -p
Check GLB status to confirm:
sudo service glb status
Test Failover Routing
Nodes in other regions can be added with a lower weight to provide failover capability:
sudo service glb add "10.0.1.110:3306:1"
We can then simulate a failure of
node0and test the connection:
sudo systemctl stop mariadb.service mysql -h 10.0.1.100 -P 13306 -u remote -p
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