Replication and High Availability

MariaDB by VSHN comes with support for multiple instances and High Availability using Galera. You have the option to configure up to two additional replicas. Please be aware of its limitations before using it.

Enable High Availability

To enable high availability you need to set the number of instances to 3, which will provision two replicas.

The following example configuration will start a MariaDB service with three replicas.

When HA is enabled, changing users via the VSHNMariaDB claim will result in a quick restart of ProxySQL. This will interrupt the connection for a few seconds. Also be aware that connections will only work via users that are specified in the claim.

apiVersion: vshn.appcat.vshn.io/v1
kind: VSHNMariaDB
metadata:
  name: mariadb-app1-prod
spec:
  parameters:
    instances: 3

Please be aware that enabling high availability will use significantly more resources and will cost three times more.

On APPUiO Cloud, it’s currently not possible to deploy more than two instances, or more than a single instance that is larger than standard-2. Please contact APPUiO Cloud support, if this blocks you from running your application.

ProxySQL

In order to optimize the connections to the Galera Cluster, a separate two node ProxySQL cluster is deployed as well. The ProxySQL cluster will manage reconnections in case of failovers. ProxySQL will identify itself as a MySQL server version 8, which is the expected behavior.

This ProxySQL will also consume certain resources in addition to Galera itself. Please consult the following table for more details.

	Requests	Limits
CPU	50m	500m
Memory	64Mi	256Mi

Requests

Limits

CPU

50m

500m

Memory

64Mi

256Mi