MySQL Enterprise Monitor is a tool to watch and analyze multiple MySQL environments from a single web based dashboard. More information is available on the MySQL homepage. Each MySQL instance is monitored by a small agent that connects to the MySQL instance and reads statistics that is sent to the MySQL Enterprise Monitor (MEM) Server.That setup is very easy. But if the MySQL server is in a cluster failover configuration, there are some things to consider when installing the MEM agent:

What do you want?

Do you want to have two entries in the MEM dashboard for both physical servers?This is good because: …

The goal is to have only one entry in the Enterprise Monitor Dashboard that shows the status of the MySQL instance, no matter on which physical server in runs. There are two ways to achieve this:

• You can install the agent on both physical nodes
• You can install the agent on a shared storage.

In either case you have to make sure, that only one agent runs at a time. You have to integrate the agent into your cluster framework. I will not describe how this works, as it is highly dependant on your cluster framework.
The following description assumes, that you will install the agent on both physical nodes.

1. Install the agent but DO NOT START the agent yet.
   
   
2. Edit the [agent-installdir]/etc/mysql-monitor-agent.ini
   In the [mysql-proxy] section add the following line:
   agent-host-id=[logical hostname]
3. …

To install the MEM agent in a way that both physical servers are listed in the MEM dashboard, you have to install the agent on both physical nodes. But: Do not start the agent after the installation!There are three different IDs in MEM: agent-uuid, mysql-uuid and host-id. Usually they are generated automatically and you will never notice these IDs. For more information about the meaning of the different IDs look at this very good explanation from Jonathon Coombes.The agent stores the uuid and the hostid in a MySQL table called mysql.inventory. After a failover the other agent on the new node will notice "wrong" hostid and uuid entries in the inventory table. The agent will stop and ask you to TRUNCATE mysql.inventory. But with this procedure MEM creates a new instance, so all old data is lost. Not good for a failover environment.So in case of a …

Here is a quick way to compile a simple MGM API application. The example will get the state of all nodes in MySQL Cluster and print whether they are connected or not.

All this without a Makefile, we just want to have some simple example on Linux to see how it works. It's basic, maybe, but sometimes useful to just have a peek.

Requirements! We assume that:

1. you installed MySQL Cluster 6.3 or higher, preferably under /usr/local/mysql,
2. your cluster is up and shiny,
3. and ndb_mgmd runs on the same machine you are compiling the MGM API test application on.

The code, save it in a file called mgmapi_test.cc …

MySQL Cluster 6.3.28 and 7.0.9 introduce the MySQL server option --ndb-wait-setup. This makes sure that clients can not connect the SQL Node when no Data Nodes are available within, by default, 15 seconds. When the timeout is reached, and no Data Nodes are available, the NDB storage engine will be marked as unavailable.

The following will appear in the MySQL server error log when --ndb-wait-setup=30 has been set:

 [Note] NDB: NodeID is 10, management server …

Funny how different experiences lead to different evaluations of tools. The MySQL HA solutions the MySQL Performanceblog list, are almost listed in the complete opposited order of what my impressions are.

Ok agreed, I should probably not put my MySQL NDB experiences from 2-3 years ago with multiple Query of deaths and more problems than you into account anymore , but back then went in the list Less stable than a single node. I've had NDB POC setups going down for much more than 05:16 minutes
Ndb comes with a lot of restrictions, there are

As for MySQL on DRBD, I've said this before , I love DRBD, but having to wait for a long InnoDB recovery after a failover just kills your uptime ,
…

Today I made a presentation to 100+ audience mostly comprising of DBAs and software consultants about MySQL Architecture and Solutions. You can download the presentation slides. This focuses on architecture overview of MySQL products and solutions.

Today I made a presentation to 100+ audience mostly comprising of DBAs and software consultants about MySQL Architecture and Solutions. You can download the presentation slides. This focuses on architecture overview of MySQL products and solutions.

Today I made a presentation to 100+ audience mostly comprising of DBAs and software consultants about MySQL Architecture and Solutions. You can download the presentation slides. This focuses on architecture overview of MySQL products and solutions.

The favourite Open Query course modules as well as reworked and brand new ones, with November/December 2009 dates for Brisbane, Sydney, Canberra and Melbourne listed below. You can register for days/modules individually, to suit your time, budget and current needs. Your trainers are Sean, Ray and Arjen (see OQ people).

For the Canberra and Melbourne days which are DBA/HA, registrations for all of the modules in a series before 15 October will receive a copy of the “High Performance MySQL” book (normal bookstore price is AUD 105).

Canberra

• Thu 5 Nov: MySQL High Availability – Strategy and Tools
• Fri 6 Nov: MySQL Cluster …