Get MySQL Cluster data nodes started after an unexpected shutdown

This article relates to MySQL version 5.1 and NDB Cluster version 6.x

When you are new to the MySQL Cluster, quite frequently, you face to the the problem of getting the data nodes attached to the cluster. Although some data nodes are started using the ndbd command, the management console shows it as disconnected. You know that there cannot be any configuration problms/errors, because you have started the cluster successfully few hours ago or the previous attempt.
In this kind of situation, most of the time, the root cause of the problem is that the cluster was ended in a improper way, in the previous time. The simple solution is starting the data nodes with the --initial option.

ndbd --initial

Reference: MySQL documentation