galera cluster

Recently I had the opportunity to have a lot of Linux systems (VMs with Rocky Linux 9) from one of our regular Galera Cluster trainings all to myself for a week. And MariaDB 11.4.4 with Galera Cluster was already installed on the machines.

Since I had long wanted to try out how a Galera Cluster behaves with an increasing number of nodes, now was the opportunity to try it out.

The following questions were to be answered:

Kürzlich hatte ich die Gelegenheit ganz viele Linux Systeme (VMs mit Rocky Linux 9) aus einer unserer regelmässig stattfindenden Galera Cluster Schulungen eine Woche lang ganz für mich alleine zur freien Verfügung zu haben. Und auf den Maschinen war auch schon ein MariaDB 11.4.4 mit Galera Cluster installiert.

Sometimes customers want to have a very simple Galera Cluster set-up. They do not want to invest into machines and build up the know-how for load balancers in front of the Galera Cluster.

We see quite often customers complaining that their Galera Cluster is not stable and "crashes" from time to time. As always one has to investigate before rating.

What comes out quite often is that the customer (or better their developers) are running huge transactions.

Because upgrading from MariaDB 10.4 to MariaDB 10.5 (non-clustered) seems not to be a problem [ 1 ] we take the challenge and try to create a receipt based on the MariaDB 10.3 to MariaDB 10.4 Galera Cluster upgrade documentation [ 3 ]:

Before you start

Before you begin with the upgrade you should consider a few things:

A while ago somebody on Google Groups asked for the Uptime of a Galera Cluster. The answer is easy... Wait, no! Not so easy... The uptime of a Galera Node is easy (or not?). But Uptime of the whole Galera Cluster?

My answer then was: "Grep the error log." My answer now is still: "Grep the error log." But slightly different:

To synchronize the data between the Galera Cluster and a new or re-entering Galera node Galera Cluster uses 2 different mechanisms:

• For full synchronization of data: Snapshot State Transfer (SST).
• For delta synchronization of data: Incremental State Transfer (IST).

The Incremental State Transfer (IST) is relevant when a node is already known to the Galera Cluster and just left the cluster short time ago. This typically happens in a maintenance window during a rolling cluster restart.

FromDual has the pleasure to announce the release of the new version 1.0.1 of the FromDual Nagios and Icinga plugins for MySQL, Galera Cluster and MariaDB.

FromDual is pleased to announce the release of a new version 1.0.0 of the Nagios and Icinga plugins for MySQL, MariaDB, Percona Server and Galera Cluster.

Any information about the changes and the new functions of the Nagios and Icinga plugins you can find here.

After properly installing and testing a Galera Cluster we see that the set-up is not finished yet. It needs something in front of the Galera Cluster that balances the load over all nodes.