is the process that is used to handle all the data in tables using the NDB Cluster storage engine\&. This is the process that empowers a data node to accomplish distributed transaction handling, node recovery, checkpointing to disk, online backup, and related tasks\&.
processes cooperate in handling data\&. These processes can execute on the same computer (host) or on different computers\&. The correspondences between data nodes and Cluster hosts is completely configurable\&.
to perform an initial start\&. An initial start erases any files created for recovery purposes by earlier instances of
\fBndbd\fR\&. It also re\-creates recovery log files\&. Note that on some operating systems this process can take a substantial amount of time\&.
.sp
An
\fB\-\-initial\fR
start is to be used
\fIonly\fR
when starting the
\fBndbd\fR
process under very special circumstances; this is because this option causes all files to be removed from the Cluster file system and all redo log files to be re\-created\&. These circumstances are listed here:
.sp
.RS4
.ien\{\
\h'-04'\(bu\h'+03'\c
.\}
.el\{\
.sp-1
.IP\(bu2.3
.\}
When performing a software upgrade which has changed the contents of any files\&.
.RE
.sp
.RS4
.ien\{\
\h'-04'\(bu\h'+03'\c
.\}
.el\{\
.sp-1
.IP\(bu2.3
.\}
When restarting the node with a new version of
\fBndbd\fR\&.
.RE
.sp
.RS4
.ien\{\
\h'-04'\(bu\h'+03'\c
.\}
.el\{\
.sp-1
.IP\(bu2.3
.\}
As a measure of last resort when for some reason the node restart or system restart repeatedly fails\&. In this case, be aware that this node can no longer be used to restore data due to the destruction of the data files\&.
.RE
.RS4
Use of this option prevents the
StartPartialTimeout
and
StartPartitionedTimeout
configuration parameters from having any effect\&.
.ifn\{\
.sp
.\}
.RS4
.it1an-trap
.nran-no-space-flag1
.nran-break-flag1
.br
.ps+1
\fBImportant\fR
.ps-1
.br
This option does
\fInot\fR
affect either of the following:
.sp
.RS4
.ien\{\
\h'-04'\(bu\h'+03'\c
.\}
.el\{\
.sp-1
.IP\(bu2.3
.\}
Backup files that have already been created by the affected node
This option also has no effect on recovery of data by a data node that is just starting (or restarting) from data nodes that are already running\&. This recovery of data occurs automatically, and requires no user intervention in a MySQL Cluster that is running normally\&.
It is permissible to use this option when starting the cluster for the very first time (that is, before any data node files have been created); however, it is
This option is used when performing a partial initial start of the cluster\&. Each node should be started with this option, as well as
\fB\-\-nowait\-nodes\fR\&.
.sp
For example, suppose you have a 4\-node cluster whose data nodes have the IDs 2, 3, 4, and 5, and you wish to perform a partial initial start using only nodes 2, 4, and 5 \(em that is, omitting node 3:
This option takes a list of data nodes which for which the cluster will not wait for before starting\&.
.sp
This can be used to start the cluster in a partitioned state\&. For example, to start the cluster with only half of the data nodes (nodes 2, 3, 4, and 5) running in a 4\-node cluster, you can start each
\fBndbd\fR
process with
\fB\-\-nowait\-nodes=3,5\fR\&. In this case, the cluster starts as soon as nodes 2 and 4 connect, and does
\fInot\fR
wait
StartPartitionedTimeout
milliseconds for nodes 3 and 5 to connect as it would otherwise\&.
.sp
If you wanted to start up the same cluster as in the previous example without one
\fBndbd\fR
\(em say, for example, that the host machine for node 3 has suffered a hardware failure \(em then start nodes 2, 4, and 5 with
\fB\-\-nowait\-nodes=3\fR\&. Then the cluster will start as soon as nodes 2, 4, and 5 connect and will not wait for node 3 to start\&.
not to start automatically\&. When this option is used,
\fBndbd\fR
connects to the management server, obtains configuration data from it, and initializes communication objects\&. However, it does not actually start the execution engine until specifically requested to do so by the management server\&. This can be accomplished by issuing the proper
process has encountered\&. Each record in this file contains a brief error string and a reference to a trace file for this crash\&. A typical entry in this file might appear as shown here:
file (see below)\&. Error log entries are thus overwritten in a cyclical and not sequential fashion\&.
.sp.5v
.RE
.RE
.sp
.RS4
.ien\{\
\h'-04'\(bu\h'+03'\c
.\}
.el\{\
.sp-1
.IP\(bu2.3
.\}
.\" MySQL Cluster: trace files
.\" trace files (MySQL Cluster)
ndb_\fInode_id\fR_trace\&.log\&.\fItrace_id\fR
is a trace file describing exactly what happened just before the error occurred\&. This information is useful for analysis by the MySQL Cluster development team\&.
.sp
It is possible to configure the number of these trace files that will be created before old files are overwritten\&.
\fBndbd\fR, it may also be necessary to specify the host name of the management server and the port on which it is listening\&. Optionally, one may also specify the node ID that the process is to use\&.
The execution process uses one thread for reading, writing, and scanning data, as well as all other activities\&. This thread is implemented asynchronously so that it can easily handle thousands of concurrent actions\&. In addition, a watch\-dog thread supervises the execution thread to make sure that it does not hang in an endless loop\&. A pool of threads handles file I/O, with each thread able to handle one open file\&. Threads can also be used for transporter connections by the transporters in the
processes which belong to different node groups; however, such a configuration is still considered experimental and is not supported for MySQL 5\&.1 in a production setting\&. See
This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License.
.PP
This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with the program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see http://www.gnu.org/licenses/.