Mariadb – Help setting up Galera Arbitrator

galeramariadbreplication

I am testing a MariaDB Galera Cluster set up with only 2 nodes, I have three servers haproxy, node1 and node2 . I was able to set it up and it worked fine until testing phase.

There are two types of test that I made:

  1. The main node fails
  2. The second node fails

While testing I came across this page which describes the problems.

So I was thinking of setting up garbd on both servers as what the guide said, but I don't think it is working(?)

Here is my garbd config:

group="galera-testing" 
address="gcomm://10.10.10.16,10.10.10.17"
options="gmcast.listen_addr=tcp://0.0.0.0:4444" 
log="/var/log/garbd.log"

If I run sudo garbd --cfg /etc/garbd.cnf the logs stop at: Note: I started this on both servers

INFO: (b363d915-923d, 'tcp://0.0.0.0:4444') turning message relay requesting off

And I can't continue using the terminal without killing it.

Now, I'm thinking of two options:

  • Setting garbd on my HAProxy Server making it act as the arbitrator or

  • Setting garbd on both nodes (im confused as the guide says to set it on both servers? what??)

Can anyone point me to the right direction? Thanks!

Note: I was able to test Galera Clusters with three nodes before + HAProxy, and it went better than with two nodes. But to satisfy my curiousity, I kinda want to learn this one works too.

Best Answer

Two node galera is a fundamentally broken design as it cannot maintain uptime without a quorum and the ability of a node to go down to aid recovery.

garb is a toy test thing and not a production tool.

Use 3 nodes all as full galera member nodes.

Use haproxy in a redundant configuration on all nodes. Use a different IP addresses for haproxy and galera without overlap.

If it can't be reliable in test then it won't be reliable in production.

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