The next four sections provide summary tables of MySQL Cluster
configuration parameters used in the
config.ini file to govern the cluster's
functioning. Each table lists the parameters for one of the
Cluster node process types (ndbd,
ndb_mgmd, and mysqld), and
includes the parameter's type as well as its default, mimimum, and
maximum values as applicable.
It is also stated what type of restart is required (node restart
or system restart) — and whether the restart must be done
--initial — to change the value of a
given configuration parameter.
When performing a node restart or an initial node restart, all of
the cluster's data nodes must be restarted in turn (also referred
to as a rolling restart). It is possible to
update cluster configuration parameters marked as
node online — that is, without shutting
down the cluster — in this fashion. An initial node restart
requires restarting each ndbd process with the
A system restart requires a complete shutdown and restart of the entire cluster. An initial system restart requires taking a backup of the cluster, wiping the cluster file system after shutdown, and then restoring from the backup following the restart.
In any cluster restart, all of the cluster's management servers must be restarted in order for them to read the updated configuration parameter values.
Values for numeric cluster parameters can generally be increased without any problems, although it is advisable to do so progressively, making such adjustments in relatively small increments. Many of these can be increased online, using a rolling restart.
However, decreasing the values of such parameters —
whether this is done via a node restart, node initial restart,
or even a complete system restart of the cluster — is not
to be undertaken lightly; it is recommended that you do so only
after careful planning and testing. This is especially true with
regard to those parameters that relate to memory usage and disk
space, such as
MaxNoOfUniqueHashIndexes. In addition, it is
the generally the case that configuration parameters relating to
memory and disk usage can be raised using a simple node restart,
but they require an initial node restart to be lowered.
Because some of these parameters can be used for configuring more than one type of cluster node, they may appear in more than one of the tables.
4294967039 — which often appears as a
maximum value in these tables — is defined in the
NDBCLUSTER sources as
MAX_INT_RNIL and is equal to
28 – 1.