17.1.5.9 Limitations Relating to Multiple MySQL Cluster Nodes

Multiple SQL nodes.  The following are issues relating to the use of multiple MySQL servers as MySQL Cluster SQL nodes, and are specific to the NDBCLUSTER storage engine:

Multiple management nodes.  When using multiple management servers:

Multiple data node processes.  While it is possible to run multiple cluster processes concurrently on a single host, it is not always advisable to do so for reasons of performance and high availability, as well as other considerations. In particular, in MySQL 5.0, we do not support for production use any MySQL Cluster deployment in which more than one ndbd process is run on a single physical machine.

Note

We may support multiple data nodes per host in a future MySQL release, following additional testing. However, in MySQL 5.0, such configurations can be considered experimental only.

Multiple network addresses.  Multiple network addresses per data node are not supported. Use of these is liable to cause problems: In the event of a data node failure, an SQL node waits for confirmation that the data node went down but never receives it because another route to that data node remains open. This can effectively make the cluster inoperable.

Note

It is possible to use multiple network hardware interfaces (such as Ethernet cards) for a single data node, but these must be bound to the same address. This also means that it not possible to use more than one [tcp] section per connection in the config.ini file. See Section 17.3.2.7, “MySQL Cluster TCP/IP Connections”, for more information.