Queries in MariaDB-Maxscale With Galera Cluster

[Suresh Kumar]

Hi

  Markus  I have certain queries, it will be helpful if u guide me for the following things

1) 

  We have 5 different App Servers these App servers have to communicate with 5 different Maxscale nodes which in Turn have to Communicate with Galera Cluster with 1 Master and 4 Salves ..

    In Our Set Up I should have 5 Midscale Nodes 5 Galera Clusters (1-Master and 4-Slaves).and also i am not clear whether this is possible .

    please guide me with possible configuration set up for my scenario

   5 - App Servers

   5 -  Maxscale Nodes

   5 -  Galera Cluster in which one Master and 4 Slaves in a Single Cluster

Flow for Single App Server  Interaction

Request:

-------------

Client - > App Server ---->MaxscaleNode----->Galera Cluster (1-Master,4-Slaves)

Response:

-------------

Galera Cluster ----->Maxscale---------->AppServer--------->Client

2) What is the Maximum number of Nodes that can be included in Galera Cluster

3) In case of if i am going to Use more than one Maxscale Node is it possible to replicate to other Maxscale Node - Galera Cluster Nodes

   Maxscale Node :1   Galera Cluster -1    Node-1,Node-2, Node-3
  

   Maxscale Node :2   Galera Cluster -2  Node-4, Node-5, Node-6

   Maxscale Node :3   Galera Cluster  -3  Node-7, Node-8, Node-9

 

    In the above case  when i write data Galera Cluster-1  in Node-1 , Node2 & Node3   will be replicated in Maxscale Node : 1.

     My doubt is whether its possible to replicate the same in all Nodes in Galera Cluster-2  Node-4, Node-5, Node-6 and Galera Cluster  -3  Node-7, Node-8, Node-9 of Maxscale Node : 2 and Maxscale Node : 3

[Markus Mäkelä]

Hi,

I think you can install MaxScale locally on the app server. This way the app can connect locally to MaxScale which then connects to the Galera cluster. I would recommend using the same cluster for all servers if the apps share the data.

As to how many nodes can be in a Galera cluster, that would be better asked on maria-...@lists.launchpad.net where a lot of people have experience with Galera setups. I don't know of any actual limits but I think around 9 nodes per cluster is the theoretical limit. I might be confusing this with something else though.

Here's a crude ASCII drawing of what I'm suggesting:

+----------+      +-----------+
|          |      |           +----------+
|   App1   +----> | MaxScale1 |          v
|          |      |           |
+----------+      +------------      +---------+
     .                  .            |         |
     .                  .            | Galera  |
     .                  .            | Cluster |
+----------+      +-----------+      |         |
|          |      |           |      +---------+
|   AppN   +----> | MaxScaleN |
|          |      |           |          ^
+----------+      +-----------+----------+

In this drawing, there's one local MaxScale on each of the app servers. This means that an application (App1) would connect through the local MaxScale (MaxScale1) to the globally shared Galera cluster.

I haven't heard of cross-cluster replication with Galera and I suspect it is not a trivial thing to achieve. I would recommend looking into using a single Galera cluster first and if it is deemed too slow, then look into having multiple Galera clusters.

Markus

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-- 
Markus Mäkelä, Software Engineer
MariaDB Corporation
t: +358 40 7740484 | Skype: markus.j.makela