There are some bug reports on the auto-discovery protocol in MySQL Cluster.
The idea of the auto-discovery protocol is to fetch the .frm files for the NDB tables stored in the data dictionary of the data nodes, and put them in the data directory of the mysql server.

However, sometimes (not always, which makes it more difficult to reproduce and hence fix), the auto-discovery seems to make strange things (from this bug report):

After shuting down and restoring my cluster I get the following error.

090211  9:59:26 [Note] NDB: mismatch in frm for panel.gatewayquestions, discovering...
090211  9:59:26 [Note] NDB Binlog: DISCOVER TABLE Event: REPL$panel/gatewayquestions
090211  9:59:26 [Note] NDB Binlog: logging ./panel/gatewayquestions (UPDATED,USE_WRITE)

This is due to the files already being in the mysql data directory. After …

In order to upgrade from 6.3 to 7.0 you must follow these rules:

1. IT IS ONLY POSSIBLE TO UPGRADE FROM 6.3 to at least 7.0.6!
2. I would recommend to upgrade from 6.3.x to 6.3.latest before doing the upgrade. If the upgrade does not work then and you have a good config.ini , you have probably hit a bug.
   
3. You cannot upgrade from 6.3 to the multi-threaded binary of 7.0.6 in one go.
   You have to upgrade from 'ndbd' (6.3) --> 'ndbd' (7.0.6)
   Then you can do 'ndbd' (7.0.6) --> 'ndbmtd' (7.0.6)

So don't try to upgrade to 7.0.5 - it will fail.
As usual when upgrading (version, configuration variables etc) you must do a rolling restart and restart:

1. ndb_mgmd (management servers)
2. ndbd (data nodes)
3. mysqld (mysql servers / direct api applications)

It isn’t necessarily immediately obvious how to set up a Cluster on LINUX; this post attempts to show how to get a simple Cluster up and running. For simplicity, all of the nodes will run on a single host – a subsequent post will take the subsequent steps of moving some of them to a second host. As with my Windows post the Cluster will contain the following nodes:

• 1 Management node (ndb_mgmd)
• 2 Data nodes (ndbd)
• 3 MySQL Server (API) nodes (mysqld)

Downloading and installing

Browse to the MySQL Cluster LINUX download page at mysql.com and download the correct version (32 or 64 bit) and store it in the desired directory (in my case, /home/billy/mysql) and then extract and …

I figured that it was time to check out how to install, configure, run and use MySQL Cluster on Windows. To keep things simple, this first Cluster will all run on a single host but includes these nodes:

• 1 Management node (ndb_mgmd)
• 2 Data nodes (ndbd)
• 3 MySQL Server (API) nodes (mysqld)

Downloading and installing

Browse to the Windows section of the MySQL Cluster 7.0 download page and download the installer (32 or 64 bit).

MySQL Cluster Windows Installer

Run the .msi file and choose the “Custom” option. Don’t worry about the fact that it’s branded as “MySQL Server 7.0″ and that you’ll go on to see adverts for MySQL Enterprise – that’s just an artefact …

MySQL Cluster version 7.0.6 has been released. MySQL Cluster 7.0.6 is available in source and binary form for a number of platforms from our download pages.

The release in source form can in addition be downloaded from the MySQL FTP server.

MySQL Cluster version 7.0.6 is using MySQL Server version 5.1.34 and contains all bug fixes and changes that MySQL Server 5.1.33 and 5.1.34 contain.
Following changes were made in MySQL Cluster 7.0.6 since the previous release 7.0.5:

Functionality added or changed:

• Important Note: It is …

There are various setups and solutions to solve the problem of having redundant mysql masters and scaling writes on them. MySQL Cluster can be an alternative. Here is why and how:
Pros:

• No need to worry about DRBD failover and recovery times
• No need to worry about potential data loss when failover from active master to standby master (has all binlog really been replicated over from the failed master?)
• Writes go to any mysql server connected to the Cluster - thus writes are easy to scale
  The data nodes will then send the committed writes to every mysql server with --log-bin enabled.
  
• MySQL Cluster can handle a lot of writes (but the slaves can become the bottleneck)
  
• Data nodes can be added online (MySQL Cluster 7.0) - …

There is another live webinar on MySQL Cluster 7.0 scheduled for 27th May 09:00 (Western European time) / 08:00 (UK time) / 11:00 (Eastern European time) and you can register here.

Alternatively, if you can’t wait that long then you can watch/listen to the play-back of the original webinar.

Note that you may need to install the WebEx Player (Windows and Mac) - unfortunately, there doesn’t seem to be a simple, supported solution for LINUX users but you can always download the slides (PDF format) from the same link or else wait until 27th May and view it live.

What’s New in the Next Generation of MySQL Cluster?
Thursday, April 30, 2009

If you are using the scripts from the Configurator (and yes, the broken link is now fixed so it is actually possible to get the config package..), and want to tweak your configuration on a started Cluster then you can do like written below.

There is also a new script in Configurator 2.2 (released 28th April 2009, PST1153AM , GMT07:53) that lets you check the values of different config parameters. Its use is described below.

Pretend we want to extend the DataMemory from 1024M to 1536M:

1. cd mysqlcluster-70/cluster/scripts
2. vi ../config/config.ini
   This is the master config.ini file and will be copied out to the management server(s). Don't change /etc/mysql/config.ini, as that will have no effect.
   
3. Set DataMemory=1536M …

Following on from the announcement  at the User Conference last week that MySQL Cluster 7.0 is now generally available, Mat Keep and I will present the first public webcast this Thursday. If you’d like to attend but the time isn’t convenient then you can either watch/listen to the recording after the event or wait for the next one to be announced (will be aimed at different time-zones).

Details…..

What’s New in the Next Generation of MySQL Cluster?
Thursday, April 30, 2009

Whether you’re racing to introduce a new service, or trying to manage an avalanche of data in real time, your database has to be scalable, fast and highly available to meet ever-changing market conditions and stringent SLAs.

By attending this webinar, you will learn more about MySQL Cluster 7, and how it enables you to deliver 99.999% database availability, with real time performance and linear scalability, while slashing …

The presentations from the sessions MySQL Cluster 7.0 - New Features and LDAP For MySQL Cluster - back-ndb, and all other sessions on MySQL Cluster, are available for download from www.mysqlconf.com.