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A Cloud Guru

Restart This Running MariaDB Galera Cluster

In this activity you are working as a DBA and have been tasked with stopping and restarting a running MariaDB Galera Cluster, to allow for data center maintenance.

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Path Info

Level

Intermediate

Duration

15m

Published

Jul 23, 2020

Challenge

Stop All Nodes
The MariaDB server needs to be stopped on all nodes:
```
sudo systemctl stop mariadb.service
```
Challenge

Determine Most Advanced Node
The grastate.dat file needs to be examined on each node, to determine which is most advanced:
```
sudo cat /var/lib/mysql/grastate.dat
```
Challenge

Bootstrap the Most Advanced Node
The following commands will be run only on the most advanced, node as determined in the previous step.

Edit node configuration in /etc/my.cnf.d/:
```
wsrep_cluster_address=gcomm://
```
Start the node:
```
sudo systemctl stop mariadb.service
```
Challenge

Check Status and Add Nodes to the Cluster
Now we can connect to the server using using the mysql client on the node we bootstrapped in the previous step:
```
mysql
```
Once connected, we can run the following SQL statement to confirm the cluster is running:
```
SHOW GLOBAL STATUS WHERE Variable_name IN ('wsrep_ready', 'wsrep_cluster_size', 'wsrep_cluster_status', 'wsrep_connected');
```
A cluster size of 1 means only one node is connected.

To join the other node to the cluster, we need to edit its configuration in /etc/my.cnf.d/. Be certain to use the private IP of the already running node for the cluster address:
```
wsrep_cluster_address=gcom://10.0.1.110
```
Start the node:
```
sudo systemctl start mariadb.service
```

Author

A Cloud Guru

The Cloud Content team comprises subject matter experts hyper focused on services offered by the leading cloud vendors (AWS, GCP, and Azure), as well as cloud-related technologies such as Linux and DevOps. The team is thrilled to share their knowledge to help you build modern tech solutions from the ground up, secure and optimize your environments, and so much more!

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