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22.3.2 Overview of NDB Cluster Configuration Parameters, Options, and Variables
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The next several sections provide summary tables of NDB Cluster
node configuration parameters used in the
config.ini file to govern various aspects of
node behavior, as well as of options and variables read by
mysqld from a my.cnf file
or from the command line when run as an NDB Cluster process. Each
of the node parameter tables lists the parameters for a given type
(ndbd, ndb_mgmd,
mysqld, computer,
tcp, shm, or
sci). All tables include the data type for the
parameter, option, or variable, as well as its default, mimimum,
and maximum values as applicable.
Considerations when restarting nodes.
For node parameters, these tables also indicate what type of
restart is required (node restart or system restart)—and
whether the restart must be done with
--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 --initial option.
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 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 using 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
MaxNoOfTables,
MaxNoOfOrderedIndexes,
and
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 often appears as a maximum value
in these tables. This value is defined in the
NDBCLUSTER sources as
MAX_INT_RNIL and is equal to
0xFFFFFEFF, or
232 −
28 − 1.
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Document créé le 26/06/2006, dernière modification le 26/10/2018
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