4 Test The MySQL Cluster

Our MySQL cluster configuration is already finished, now it's time to test it. On the cluster management server (loadb1.example.com), run the cluster management client ndb_mgm to check if the cluster nodes are connected:

mysql-mngt.example.com:

ndb_mgm

You should see this:

-- NDB Cluster -- Management Client --
ndb_mgm>

Now type show; at the command prompt:

show;

The output should be like this:

ndb_mgm> show;
Connected to Management Server at: localhost:1186
Cluster Configuration
---------------------
[ndbd(NDB)] 2 node(s)
id=2 @10.0.1.33 (Version: 5.1.24, Nodegroup: 0, Master)
id=3 @10.0.1.34 (Version: 5.1.24, Nodegroup: 0)

[ndb_mgmd(MGM)] 1 node(s)
id=1 @10.0.1.30 (Version: 5.1.24)

[mysqld(API)] 2 node(s)
id=4 @10.0.1.34 (Version: 5.1.24)
id=5 @10.0.1.33 (Version: 5.1.24)

ndb_mgm>

If you see that your nodes are connected, then everything's ok!

Type

quit;

to leave the ndb_mgm client console.

Now we have to create a test database with a test table and some data on mysql-data1.example.com:

mysql-data1.example.com:

mysql -u root -p
CREATE DATABASE mysqlclustertest;
USE mysqlclustertest;
CREATE TABLE testtable (I INT) ENGINE=NDBCLUSTER;
INSERT INTO testtable () VALUES (1);
SELECT * FROM testtable;
quit;

(Have a look at the CREATE statement: We must use ENGINE=NDBCLUSTER for all database tables that we want to get clustered! If you use another engine, then clustering will not work!)

The result of the SELECT statement should be:

mysql> SELECT * FROM testtable;
+------+
| I    |
+------+
| 1    |
+------+
1 row in set (0.03 sec)

Now we have to create the same database on sql2.example.com (yes, we still have to create it, but afterwards testtable and its data should be replicated to mysql-data2.example.com because testtable uses ENGINE=NDBCLUSTER):

mysql-data2.example.com:

mysql -u root -p
CREATE DATABASE mysqlclustertest;
USE mysqlclustertest;
SELECT * FROM testtable;

The SELECT statement should deliver you the same result as before on mysql-data1.example.com: [The CREATE statement should fail due to NDBCLUSTER Engine]

mysql> SELECT * FROM testtable;
+------+
| I    |
+------+
| 1    |
+------+
1 row in set (0.04 sec)

So the data was replicated from mysql-data1.example.com to mysql-data2.example.com. Now we insert another row into testtable:

mysql-data2.example.com:

INSERT INTO testtable () VALUES (2);
quit;

Now let's go back to mysql-data1.example.com and check if we see the new row there:

mysql-data1.example.com:

mysql -u root -p
USE mysqlclustertest;
SELECT * FROM testtable;
quit;

You should see something like this:

mysql> SELECT * FROM testtable;
+------+
| I    |
+------+
| 1    |
| 2    |
+------+
2 rows in set (0.05 sec)

So both MySQL cluster nodes always have the same data!

Now let's see what happens if we stop node 1 (mysql-data1.example.com): Run

mysql-data1.example.com:

killall ndbd

and check with

ps aux | grep ndbd | grep -iv grep

that all ndbd processes have terminated. If you still see ndbd processes, run another

killall ndbd

until all ndbd processes are gone.

Now let's check the cluster status on our management server (mysql-mngt.example.com):

mysql-mngt.example.com:

ndb_mgm

On the ndb_mgm console, issue

show;

and you should see this:

ndb_mgm> show;
Connected to Management Server at: localhost:1186
Cluster Configuration
---------------------
[ndbd(NDB)] 2 node(s)
id=2 (not connected, accepting connect from 10.0.1.33)
id=3 @10.0.1.34 (Version: 5.1.24, Nodegroup: 0, Master)

[ndb_mgmd(MGM)] 1 node(s)
id=1 @10.0.1.30 (Version: 5.1.24)

[mysqld(API)] 2 node(s)
id=4 @10.0.1.34 (Version: 5.1.24)
id=5 @10.0.1.33 (Version: 5.1.24)

ndb_mgm>

You see, mysql-data1.example.com is not connected anymore.

Type

quit;

to leave the ndb_mgm console.

Let's check mysql-data2.example.com:

mysql-data2.example.com:

mysql -u root -p
USE mysqlclustertest;
SELECT * FROM testtable;
quit;

The result of the SELECT query should still be

mysql> SELECT * FROM testtable;
+------+
| I    |
+------+
| 1    |
| 2    |
+------+
2 rows in set (0.17 sec)

Ok, all tests went fine, so let's start our mysql-data1.example.com node again:

mysql-data1.example.com:

ndbd