Oracle Linux/MySQL

Simple Cluster configuration

Will consist of 5 components:

Management Node

holds the configuration for MySQL Cluster in a file called config.ini. It also writes a cluster log, and takes part in arbitration to prevent split-brain or network partitioning.

(2) Data Nodes

stores the data and the tables. The data nodes takes cares of managing the transactions, recovery, etc

(2) SQL Nodes

the most common way to read/write data to the Data Nodes is by using the MySQL Server (aka SQL Node)

Management Node Configuration

dependencies

While most of the guides I found perform installation directly using the RPM packages, I prefer to install packages from a repository whenever available. MySQL provides a YUM repository.

~$ wget https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm
~$ sudo yum localinstall -y mysql80-community-release-el7-3.noarch.rpm

Verify you can see the new cluster packages and search them.

~$ yum repolist all | grep mysql
~$ yum --enablerepo=mysql-cluster-8.0-community search mysql

Enable the cluster repo by setting enabled=1

~$ sudo vim /etc/yum.repos.d/mysql-community.repo
...
[mysql-cluster-8.0-community]
name=MySQL Cluster 8.0 Community
baseurl=http://repo.mysql.com/yum/mysql-cluster-8.0-community/el/7/$basearch/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

Do a quick check-update to refresh the package list cache

~$ sudo yum check-update

We also need to open a port and make sure our networking interface is setup correctly. In my environment, servers communicate with each other through a virtual 10GB network rather than traversing the physical 1GB network.

~$ sudo firewall-cmd --permanent --zone=internal --change-interface=eth1
~$ sudo firewall-cmd --zone=internal --permanent --add-port=1186/tcp

Lastly, there are some other packages you may need to install, but are not required. More info can be found here.

~$ sudo yum install -y telnet vim net-tools bind-utils

package installation

There are a couple of dependencies we need to install.

~$ sudo yum install -y epel-release && sudo yum install -y perl-Class-MethodMaker

Install the packages

 ~$ sudo yum install -y mysql-cluster-community-management-server mysql-cluster-community-client mysql-cluster-community-libs

Configure cluster

Now we can setup a basic configuration file for the cluster.

~$ sudo mkdir -p /var/lib/mysql-cluster
~$ sudo vim /var/lib/mysql-cluster/config.ini
...
[ndb_mgmd default]
# Directory for MGM node log files
DataDir=/var/lib/mysql-cluster

[ndb_mgmd]
#Management Node db1
HostName=rncv-sqlmgmt01.virtual.local

[ndbd default]
NoOfReplicas=2      # Number of replicas
DataMemory=256M     # Memory allocate for data storage
IndexMemory=128M    # Memory allocate for index storage
#Directory for Data Node
DataDir=/var/lib/mysql-cluster

[ndbd]
#Data Node db2
HostName=rncv-sqldata01.virtual.local

[ndbd]
#Data Node db3
HostName=rncv-sqldata02.virtual.local

[mysqld]
#SQL Node db4
HostName=rncv-sql01.virtual.local

[mysqld]
#SQL Node db5
HostName=rncv-sql02.virtual.local

Now we can implement the config

~$ sudo ndb_mgmd --config-file=/var/lib/mysql-cluster/config.ini
MySQL Cluster Management Server mysql-8.0.19 ndb-8.0.19
2020-02-24 17:54:57 [MgmtSrvr] INFO     -- The default config directory '/usr/mysql-cluster' does not exist. Trying to create it...
2020-02-24 17:54:57 [MgmtSrvr] INFO     -- Sucessfully created config directory
2020-02-24 17:54:57 [MgmtSrvr] WARNING  -- at line 12: [DB] IndexMemory is deprecated, will use Number bytes on each ndbd(DB) node allocated for storing indexes instead

And finally we can view the implementation:

~$ ndb_mgm
-- NDB Cluster -- Management Client --
ndb_mgm> show
Connected to Management Server at: localhost:1186
Cluster Configuration
---------------------
[ndbd(NDB)]	2 node(s)
id=2 (not connected, accepting connect from rncv-sqldata01.virtual.local)
id=3 (not connected, accepting connect from rncv-sqldata02.virtual.local)

[ndb_mgmd(MGM)]	1 node(s)
id=1	@10.10.0.40  (mysql-8.0.19 ndb-8.0.19)

[mysqld(API)]	2 node(s)
id=4 (not connected, accepting connect from rncv-sql01.virtual.local)
id=5 (not connected, accepting connect from rncv-sql02.virtual.local)

ndb_mgm> quit