Backup of Galera is not a complicated task; it just requires organization. This is simply because when you're doing a backup, your node goes in Donor mode. Using Xtrabackup will reduce the Donor mode time as compared to a classical dump and helps in quickly integrating a new node.

If you want to back up a Galera node with mysqldump, it is strongly recommended to use a load balancer (such as HAProxy) to move out the cluster node that provides data for backups. If you put in place what has been seen in Chapter 8, Galera Cluster – Multimaster Replication, there won't be any problem. When a node is in Donor mode, it will automatically be removed from the load balancer and will automatically be reintegrated while it gets finished and synced.

If you have no special constraints and can use Xtrabackup, it's better. To create a backup, you need to add a new option dedicated for Galera Cluster, which will create a xtrabackup_galera_info file with Galera information inside. If you do not...