High Availability

Overview

Enterprise applications often require the ability to run continuously for extended periods of time with little or no user-facing downtime.

High Availability Solutions

MariaDB Enterprise X6 supports several different high availability solutions.

MariaDB Replication

MariaDB Replication supports high availability.

Replica servers replicate data from a primary server asynchronously or semi-synchronously using binary logs. Upon primary server failure, a replica server can be promoted to a primary server.

Galera Cluster

Galera Cluster supports high availability.

Cluster nodes replicate data using certification-based replication implemented by the Galera 3 or Galera 4 plugin, depending on the version of MariaDB. Upon node failure, the cluster automatically recovers, as long as remaining nodes have quorum.

MariaDB Enterprise ColumnStore

MariaDB Enterprise ColumnStore supports high availability in multi-node deployments.

ColumnStore nodes share data using shared storage. Upon node failure, shared storage can still be accessed by remaining nodes.

MariaDB Xpand

MariaDB Xpand supports high availability.

Xpand divides tables and indexes into slices, and it distributes those slices among all the nodes. Xpand maintains replicas of each slice, so that it can recover from a node failure without loss of data.

MariaDB Xpand supports multiple topologies. Several options are described below. MariaDB products can be deployed in many different topologies. The topologies on this page are representative. MariaDB products can be deployed to form other topologies, leverage advanced product capabilities, or combine the capabilities of multiple topologies.

Xpand Performance Topology

MariaDB Xpand Performance topology delivers maximum throughput and lowest latency.

Xpand Storage Engine Topology

Xpand Storage Engine topology leverages Xpand's benefits and maximize compatibility with MariaDB Enterprise Server (ES). It allows Xpand users to leverage ES features like window functions, CTEs, and cross-engine JOINs.

For additional information, see "MariaDB Xpand Topologies".

Automatic Failover with MaxScale

MariaDB MaxScale augments MariaDB Enterprise's HA solutions with additional automatic failover capabilities. The specific capabilities depend on the high availability solution that is used:

HA Solution

Description

MariaDB Replication

MaxScale's MariaDB Monitor (mariadbmon) detects primary server failure and promotes the most up-to-date replica based on Global Transaction ID (GTID), waits for that replica to execute any transactions in its relay log, and begins routing queries to it.

Galera Cluster

MaxScale's Galera Monitor (galeramon) is used to minimize application impact upon server failure. Additionally, MaxScale may be used to assign primary and replica roles to database instances within a cluster to support read/write traffic splitting and to minimize the risk of certification failures.

MariaDB Enterprise ColumnStore

MaxScale's MariaDB Monitor (mariadbmon) determines which node is the primary server, and automatically performs failover upon primary server failure.

MariaDB Xpand Performance Topology

MaxScale's Xpand Monitor (xpandmon) determine which nodes are currently part of the deployment, and it only routes connections to nodes that are available.

MariaDB Xpand Storage Engine Topology

MaxScale's MariaDB Monitor (mariadbmon) determine which node is the primary server, and automatically performs failover upon primary server failure.

MaxScale's Read/Write Split Router (readwritesplit) includes several configurable features to minimize the impact of failover on client connections:

Feature

Description

Automatic Reconnection

Replaces back-end server connections to a failed server with connections to a different server, rather than closing the connections.

Transaction Replay

Ensures the execution of prior transactions before additional queries are routed to different Servers, instead of closing the connection and requiring the application to roll the transaction back and retry.

Connection Maintenance and Restore

Ensures all servers handling traffic for a connection have the same session system variables, user-defined variables, etc.

Read Retry

Allows MaxScale to route incomplete queries to a different replica rather than returning an error or closing the client connection.

Delayed Retry

Allows MaxScale to delay and retry write queries received after a primary fails and before automatic failover completes, rather than returning an error or closing the client connection

Deploy MariaDB Xpand

MariaDB Xpand provides distributed SQL, high availability, fault tolerance, write scaling, and horizontal scale-out for transactional workloads. It is available in a standalone topology and in a topology with MariaDB Enterprise Server using the Xpand storage engine. Both topologies support high availability.

To deploy MariaDB Xpand, choose a topology:

Topology

Description

Xpand Performance

  • Delivers maximum throughput and lowest latency.

  • Uses MaxScale as a transparent database proxy to monitor node health and route queries to Xpand nodes.

  • Xpand stores data in a distributed manner and executes queries using parallel query evaluation.

Xpand Storage Engine

  • Leverages Xpand's benefits and maximizes compatibility with MariaDB Enterprise Server (ES).

  • Uses MaxScale as a transparent database proxy to monitor node health and route queries to ES nodes.

  • ES nodes store non-Xpand tables and interact with Xpand tables using the Xpand Storage Engine.

  • Xpand stores data for Xpand tables in a distributed manner and executes queries using parallel query evaluation.

For additional information, see "MariaDB Xpand Topologies".