Using SST Donors for Queries with MaxScale's Galera Monitor

This page is part of MariaDB's Documentation.

The parent of this page is: Galera Monitor

Topics on this page:

Overview
Non-Blocking SST Methods
Configuring Availability of SST Donors

Overview

MaxScale's Galera Monitor (galeramon) monitors Galera Cluster Galera Cluster deployments.

By default, when a node is chosen as a donor for a State Snapshot Transfer (SST), Galera Monitor does not route any queries to it. However, some SST methods are non-blocking on the donor, so this default behavior is not always desired.

Non-Blocking SST Methods

A cluster's SST method is defined by the wsrep_sst_method system variable. When this system variable is set to mariabackup, the cluster uses MariaDB Backup MariaDB Backup to perform the SST. MariaDB Backup MariaDB Backup is a non-blocking backup method, so Galera Cluster allows the node to execute queries while acting as the SST donor.

Configuring Availability of SST Donors

Configure the availability of SST donors by configuring the available_when_donor parameter for the Galera Monitor in maxscale.cnf.

For example:

[galera-cluster]
type                     = monitor
module                   = galeramon
...
available_when_donor     = true

Restart the MaxScale instance.
```
$ sudo systemctl restart maxscale
```