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A Cloud Guru

Recover This Crashed MariaDB Galera Cluster

In this activity you are working as a DBA and have been tasked with recovering a crashed MariaDB Galera cluster.

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Path Info

Level

Intermediate

Duration

15m

Published

Jul 23, 2020

Challenge

Determine the Most Advanced Node
We can check the sequence number of the node:
```
sudo -u mysql mysqld --wsrep_recover
```
Run this on all nodes, and the highest sequence number is the most advanced node.
Challenge

Bootstrap the Most Advanced Node
Edit the node configuration in /etc/my.cnf.d/:
```
wsrep_cluster_address=gcomm://
```
Start the node:
```
sudo systemctl start mariadb.service
```
Challenge

Check Status and Add Nodes to the Cluster
Connect with mysql client and query status variables:
```
SHOW GLOBAL STATUS WHERE Variable_name IN ('wsrep_ready', 'wsrep_cluster_size', 'wsrep_cluster_status', 'wsrep_connected');
```
Edit the node configuration in /etc/my.cnf.d/. Be certain to use the private IP of the running node:
```
wsrep_cluster_address=gcom://10.0.0.110
```
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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