25.6.1 Commands in the NDB Cluster Management Client (original) (raw)

25.6.1 Commands in the NDB Cluster Management Client

In addition to the central configuration file, a cluster may also be controlled through a command-line interface available through the management client ndb_mgm. This is the primary administrative interface to a running cluster.

Commands for the event logs are given inSection 25.6.3, “Event Reports Generated in NDB Cluster”; commands for creating backups and restoring from them are provided inSection 25.6.8, “Online Backup of NDB Cluster”.

Using ndb_mgm with MySQL Cluster Manager. MySQL Cluster Manager 1.4.8 provides experimental support for NDB 8.0. MySQL Cluster Manager handles starting and stopping processes and tracks their states internally, so it is not necessary to usendb_mgm for these tasks for an NDB Cluster that is under MySQL Cluster Manager control. It is recommended_not_ to use the ndb_mgm command-line client that comes with the NDB Cluster distribution to perform operations that involve starting or stopping nodes. These include but are not limited to theSTART,STOP,RESTART, andSHUTDOWN commands. For more information, see MySQL Cluster Manager Process Commands.

The management client has the following basic commands. In the listing that follows, nodeid denotes either a data node ID or the keyword ALL, which indicates that the command should be applied to all of the cluster's data nodes.

id=3    @10.100.2.67  (8.0.42-ndb-8.0.42, no nodegroup)

DROP NODEGROUP works only when all data nodes in the node group to be dropped are completely empty of any table data and table definitions. Since there is currently no way using ndb_mgm or themysql client to remove all data from a specific data node or node group, this means that the command succeeds only in the two following cases:
1. After issuing CREATE NODEGROUP in the ndb_mgm client, but before issuing anyALTER TABLE ... REORGANIZE PARTITION statements in themysql client.
2. After dropping all NDBCLUSTER tables using DROP TABLE.
TRUNCATE TABLE does not work for this purpose because this removes only the table data; the data nodes continue to store anNDBCLUSTER table's definition until a DROP TABLE statement is issued that causes the table metadata to be dropped.
For more information about DROP NODEGROUP, see Section 25.6.7, “Adding NDB Cluster Data Nodes Online”. * ENTER SINGLE USER MODE_node_id_
Enters single user mode, whereby only the MySQL server identified by the node ID nodeid is permitted to access the database.
The ndb_mgm client provides a clear acknowledgement that this command has been issued and has taken effect, as shown here:
ndb_mgm> ENTER SINGLE USER MODE 100 Single user mode entered Access is granted for API node 100 only.
In addition, the API or SQL node having exclusive access when in single user mode is indicated in the output of theSHOW command, like this:
```
ndb_mgm> SHOW
Cluster Configuration

[ndbd(NDB)] 2 node(s)
id=5 @127.0.0.1 (mysql-8.0.42 ndb-8.0.42, single user mode, Nodegroup: 0, )
id=6 @127.0.0.1 (mysql-8.0.42 ndb-8.0.42, single user mode, Nodegroup: 0)
[ndb_mgmd(MGM)] 1 node(s)
id=50 @127.0.0.1 (mysql-8.0.42 ndb-8.0.42)
[mysqld(API)] 2 node(s)
id=100 @127.0.0.1 (mysql-8.0.42 ndb-8.0.42, allowed single user)
id=101 (not connected, accepting connect from any host)
* [EXIT SINGLE USER MODE](mysql-cluster-mgm-client-commands.html#ndbclient-exit-single-user-mode) Exits single user mode, enabling all SQL nodes (that is, all running [**mysqld**](mysqld.html "6.3.1 mysqld — The MySQL Server") processes) to access the database. Note It is possible to use `EXIT SINGLE USER MODE` even when not in single user mode, although the command has no effect in this case. * [HELP](mysql-cluster-mgm-client-commands.html#ndbclient-help) Displays information on all available commands. * [_node\_id_ NODELOG DEBUG {ON|OFF}](mysql-cluster-mgm-client-commands.html#ndbclient-nodelog-debug) Toggles debug logging in the node log, as though the effected data node or nodes had been started with the[\--verbose](mysql-cluster-programs-ndbd.html#option%5Fndbd%5Fverbose) option.`NODELOG DEBUG ON` starts debug logging;`NODELOG DEBUG OFF` switches debug logging off. * [PROMPT \[_prompt_\]](mysql-cluster-mgm-client-commands.html#ndbclient-prompt) Changes the prompt shown by [**ndb\_mgm**](mysql-cluster-programs-ndb-mgm.html "25.5.5 ndb_mgm — The NDB Cluster Management Client") to the string literal _`prompt`_. _`prompt`_ should not be quoted (unless you want the prompt to include the quotation marks). Unlike the case with the [**mysql**](mysql.html "6.5.1 mysql — The MySQL Command-Line Client") client, special character sequences and escapes are not recognized. If called without an argument, the command resets the prompt to the default value (`ndb_mgm>`). Some examples are shown here:
ndb_mgm> PROMPT mgm#1:
mgm#1: SHOW
Cluster Configuration
...
mgm#1: PROMPT mymgm >
mymgm > PROMPT 'mymgm:'
'mymgm:' PROMPT mymgm:
mymgm: PROMPT
ndb_mgm> EXIT
$>
Note that leading spaces and spaces within the_`prompt`_ string are not trimmed. Trailing spaces are removed. * [QUIT](mysql-cluster-mgm-client-commands.html#ndbclient-quit),[EXIT](mysql-cluster-mgm-client-commands.html#ndbclient-quit) Terminates the management client. This command does not affect any nodes connected to the cluster. * [_node\_id_ REPORT _report-type_](mysql-cluster-mgm-client-commands.html#ndbclient-report) Displays a report of type_`report-type`_ for the data node identified by _`nodeid`_, or for all data nodes using `ALL`. Currently, there are three accepted values for_`report-type`_: * `BackupStatus` provides a status report on a cluster backup in progress * `MemoryUsage` displays how much data memory and index memory is being used by each data node as shown in this example:
ndb_mgm> ALL REPORT MEMORY
Node 1: Data usage is 5%(177 32K pages of total 3200)
Node 1: Index usage is 0%(108 8K pages of total 12832)
Node 2: Data usage is 5%(177 32K pages of total 3200)
Node 2: Index usage is 0%(108 8K pages of total 12832)
```
This information is also available from thendbinfo.memoryusage table.
* EventLog reports events from the event log buffers of one or more data nodes.
_report-type_ is case-insensitive and“fuzzy”; for MemoryUsage, you can use MEMORY (as shown in the prior example), memory, or even simplyMEM (or mem). You can abbreviate BackupStatus in a similar fashion. * node_id RESTART [-n] [-i] [-a] [-f]
Restarts the data node identified by_nodeid_ (or all data nodes).
Using the -i option withRESTART causes the data node to perform an initial restart; that is, the node's file system is deleted and recreated. The effect is the same as that obtained from stopping the data node process and then starting it again using ndbd --initial from the system shell.
Note
Backup files and Disk Data files are not removed when this option is used.
Using the -n option causes the data node process to be restarted, but the data node is not actually brought online until the appropriateSTART command is issued. The effect of this option is the same as that obtained from stopping the data node and then starting it again usingndbd --nostart or ndbd -n from the system shell.
Using the -a causes all current transactions relying on this node to be aborted. No GCP check is done when the node rejoins the cluster.
Normally, RESTART fails if taking the node offline would result in an incomplete cluster. The-f option forces the node to restart without checking for this. If this option is used and the result is an incomplete cluster, the entire cluster is restarted. * SHOW
Displays basic information about the cluster and cluster nodes. For all nodes, the output includes the node's ID, type, and NDB software version. If the node is connected, its IP address is also shown; otherwise the output shows not connected, accepting connect from_`ipaddress`_, withany host used for nodes that are permitted to connect from any address.
In addition, for data nodes, the output includesstarting if the node has not yet started, and shows the node group of which the node is a member. If the data node is acting as the master node, this is indicated with an asterisk (`). Consider a cluster whose configuration file includes the information shown here (possible additional settings are omitted for clarity): ``` [ndbd default] DataMemory= 128G NoOfReplicas= 2 [ndb_mgmd] NodeId=50 HostName=198.51.100.150 [ndbd] NodeId=5 HostName=198.51.100.10 DataDir=/var/lib/mysql-cluster [ndbd] NodeId=6 HostName=198.51.100.20 DataDir=/var/lib/mysql-cluster [ndbd] NodeId=7 HostName=198.51.100.30 DataDir=/var/lib/mysql-cluster [ndbd] NodeId=8 HostName=198.51.100.40 DataDir=/var/lib/mysql-cluster [mysqld] NodeId=100 HostName=198.51.100.100 [api] NodeId=101 ``` After this cluster (including one SQL node) has been started,SHOW` displays the following output:
```
ndb_mgm> SHOW
Connected to Management Server at: localhost:1186
Cluster Configuration

[ndbd(NDB)] 4 node(s)
id=5 @198.51.100.10 (mysql-8.0.42 ndb-8.0.42, Nodegroup: 0, *)
id=6 @198.51.100.20 (mysql-8.0.42 ndb-8.0.42, Nodegroup: 0)
id=7 @198.51.100.30 (mysql-8.0.42 ndb-8.0.42, Nodegroup: 1)
id=8 @198.51.100.40 (mysql-8.0.42 ndb-8.0.42, Nodegroup: 1)
[ndb_mgmd(MGM)] 1 node(s)
id=50 @198.51.100.150 (mysql-8.0.42 ndb-8.0.42)
[mysqld(API)] 2 node(s)
id=100 @198.51.100.100 (mysql-8.0.42 ndb-8.0.42)
id=101 (not connected, accepting connect from any host)

```
The output from this command also indicates when the cluster is in single user mode (see the description of theENTER SINGLE USER MODE command, as well asSection 25.6.6, “NDB Cluster Single User Mode”). In NDB 8.0, it also indicates which API or SQL node has exclusive access when this mode is in effect; this works only when all data nodes and management nodes connected to the cluster are running NDB 8.0.

Additional commands. A number of other commands available in thendb_mgm client are described elsewhere, as shown in the following list: