replication

MySQL Fabric – Part 1 – Installing

MySQL Fabric is a tool included on MySQL Utilities that helps you to manage your MySQL instances.
It works by basically adding a new layer between your application and MySQL instances, which can provide an easy way to use sharding and build a highly available system.

To install our Fabric environment, we will have to configure 4 servers, I will use the follow names and IP on this tutorial:

fabric1 (192.168.0.200) - fabric
mysql1 (192.168.0.201) - mysql master
mysql2 (192.168.0.202) - mysql slave
mysql3 (192.168.0.203) - mysql slave

Note: I’m running CentOS 6.5 on all servers.

1. Add mysql repo on all 4 machines, please read Installing latest version of MySQL via yum for more info:

rpm -i http://dev.mysql.com/get/mysql-community-release-el6-5.noarch.rpm
yum update

2. Install mysql mysql-server mysql-utilities:

yum install mysql mysql-server mysql-utilities
chkconfig mysqld on
/etc/init.d/mysqld start

3. On mysql1,mysql2,mysql3 add the follow to my.cnf:

[mysqld]
...
binlog-format=ROW
log-slave-updates=true
gtid-mode=on
enforce-gtid-consistency=true
master-info-repository=TABLE
relay-log-info-repository=TABLE
sync-master-info=1
report-host=192.168.0.201
report-port=3306
server-id=1
log-bin=mysql1-bin.log

4. On mysql1 add a replication user for each mysql ip:


GRANT REPLICATION SLAVE ON *.* TO replication@192.168.0.201 IDENTIFIED BY 'reppwd';
GRANT REPLICATION SLAVE ON *.* TO replication@192.168.0.202 IDENTIFIED BY 'reppwd';
GRANT REPLICATION SLAVE ON *.* TO replication@192.168.0.203 IDENTIFIED BY 'reppwd';

[root@mysql1 ~]# mysql -u root -e "GRANT REPLICATION SLAVE ON *.* TO replication@192.168.0.201 IDENTIFIED BY 'reppwd'; "
[root@mysql1 ~]# mysql -u root -e "GRANT REPLICATION SLAVE ON *.* TO replication@192.168.0.202 IDENTIFIED BY 'reppwd'; "
[root@mysql1 ~]# mysql -u root -e "GRANT REPLICATION SLAVE ON *.* TO replication@192.168.0.203 IDENTIFIED BY 'reppwd'; "

5. On mysql1 add the privileges to fabric user from fabric node ip:


GRANT ALL ON *.* TO 'replication'@'192.168.0.200' IDENTIFIED BY 'reppwd';

[root@mysql1 ~]# mysql -u root -e "GRANT ALL ON *.* TO 'replication'@'192.168.0.200' IDENTIFIED BY 'reppwd';"

6. On mysql2 and mysql3, setup replication:

CHANGE MASTER TO MASTER_HOST='192.168.0.201', MASTER_USER='replication', MASTER_PASSWORD='reppwd', MASTER_AUTO_POSITION=1;
START SLAVE;

7. On fabric1, add the fabric MySQL user:


GRANT ALL ON fabric.* TO 'fabric'@'localhost' IDENTIFIED BY 'fabricpwd';

[root@fabric1 ~]# mysql -u root -e "GRANT ALL ON fabric.* TO 'fabric'@'localhost' IDENTIFIED BY 'fabricpwd';"

8. On fabric1,, configure user and password on [storage] and [servers] group on /etc/mysql/fabric.cfg :

[storage]
...
password = fabricpwd
...
[servers]
password = reppwd
user = replication

9. On fabric1, start the fabric db, it will ask to create a password, this password will be used on all next mysqlfabric commands:


mysqlfabric manage setup

[root@fabric1 ~]# mysqlfabric manage setup
[INFO] 1406131468.176740 - MainThread - Initializing persister: user (fabric), server (localhost:3306), database (fabric).
Finishing initial setup
=======================
Password for admin user is not yet set.
Password for admin/xmlrpc: 
Repeat Password:
Password set.

10. On fabric1, start fabric:


mysqlfabric manage start &

11. On fabric1,, add a group:

mysqlfabric group create GLOBAL1

[root@fabric1 ~]# mysqlfabric group create GLOBAL1
Password for admin: 
Procedure :
{ uuid        = 5e4a6bdb-60f0-4e34-87ba-4c56b7616b35,
  finished    = True,
  success     = True,
  return      = True,
  activities  = 
}

12. On fabric1,, add mysql1, mysql2 and mysql3 to GLOBAL1 group:


mysqlfabric group add GLOBAL1 192.168.0.201
mysqlfabric group add GLOBAL1 192.168.0.202
mysqlfabric group add GLOBAL1 192.168.0.203

[root@fabric1 ~]# mysqlfabric group add GLOBAL1 192.168.0.201
Password for admin: 
Procedure :
{ uuid        = 39efb9c4-6195-4c41-aa02-0bfdc228bfe2,
  finished    = True,
  success     = True,
  return      = True,
  activities  = 
}
[root@fabric1 ~]# mysqlfabric group add GLOBAL1 192.168.0.202
Password for admin: 
Procedure :
{ uuid        = c8babfb9-d836-44c0-b4fd-015cd1df8298,
  finished    = True,
  success     = True,
  return      = True,
  activities  = 
}
[root@fabric1 ~]# mysqlfabric group add GLOBAL1 192.168.0.203
Password for admin: 
Procedure :
{ uuid        = c86bba70-69ac-4923-9c54-1a8aaab6d97e,
  finished    = True,
  success     = True,
  return      = True,
  activities  = 
}

13. On fabric1, get the uuid of your master:

mysqlfabric group lookup_servers GLOBAL1

[root@fabric1 ~]# mysqlfabric group lookup_servers GLOBAL1
Password for admin: 
Command :
{ success     = True
  return      = [{'status': 'SECONDARY', 'server_uuid': '2e157d1e-1281-11e4-80dc-080027aa0242', 'mode': 'READ_ONLY', 'weight': 1.0, 'address': '192.168.0.201'}, {'status': 'SECONDARY', 'server_uuid': '41d85bee-1281-11e4-80dc-080027e87bc6', 'mode': 'READ_ONLY', 'weight': 1.0, 'address': '192.168.0.202'}, {'status': 'SECONDARY', 'server_uuid': '472734d8-1281-11e4-80dc-0800274a710c', 'mode': 'READ_ONLY', 'weight': 1.0, 'address': '192.168.0.203'}]
  activities  = 
}

14. On fabric1, add your master as master on GLOBAL1 group:

mysqlfabric group promote GLOBAL1 --slave_id='2e157d1e-1281-11e4-80dc-080027aa0242'

[root@fabric1 ~]# mysqlfabric group promote GLOBAL1 --slave_id='2e157d1e-1281-11e4-80dc-080027aa0242'
Password for admin: 
[WARNING] 1406131951.712366 - Executor-2 - Error () trying to process transactions in the relay log for candidate (('Command (START SLAVE SQL_THREAD, ()) failed: 1200 (HY000): The server is not configured as slave; fix in config file or with CHANGE MASTER TO', 1200)).
[INFO] 1406131951.824763 - Executor-2 - Master has changed from None to 2e157d1e-1281-11e4-80dc-080027aa0242.
Procedure :
{ uuid        = 733ae69d-fb12-447b-b86b-041703491315,
  finished    = True,
  success     = True,
  return      = True,
  activities  = 
}
[root@fabric1 ~]# mysqlfabric group lookup_servers GLOBAL1
Password for admin: 
Command :
{ success     = True
  return      = [{'status': 'PRIMARY', 'server_uuid': '2e157d1e-1281-11e4-80dc-080027aa0242', 'mode': 'READ_WRITE', 'weight': 1.0, 'address': '192.168.0.201'}, {'status': 'SECONDARY', 'server_uuid': '41d85bee-1281-11e4-80dc-080027e87bc6', 'mode': 'READ_ONLY', 'weight': 1.0, 'address': '192.168.0.202'}, {'status': 'SECONDARY', 'server_uuid': '472734d8-1281-11e4-80dc-0800274a710c', 'mode': 'READ_ONLY', 'weight': 1.0, 'address': '192.168.0.203'}]
  activities  = 
}
[root@fabric1 ~]# 

That is it, we now have our MySQL Fabric environment working and ready.
Watch out for my next few posts to learn more about MySQL Fabric.

MySQL Sandbox

Hi there, today we will learn about an amazing tool that every single MySQL dba must know, I’m talking about MySQL Sandbox.

MySQL Sandbox is developed by Giuseppe Maxia (The Data Charmer), it’s a tool that make the installation of MySQL servers very easy. If you need to quickly create a MySQL instance for test or a replication setup(it supports master slave, circular and master master replication), this it the tool.

INSTALLATION:

Go to http://mysqlsandbox.net/ and get the latest version (I got from launchpad):

yum install perl perl-ExtUtils-MakeMaker perl-Test-Simple
wget https://launchpad.net/mysql-sandbox/mysql-sandbox-3/mysql-sandbox-3/+download/MySQL-Sandbox-3.0.44.tar.gz
tar -zxvf MySQL-Sandbox-3.0.44.tar.gz
cd MySQL-Sandbox-3.0.44
perl Makefile.PL
make
make test
make install

CREATING A SINGLE SANDBOX:

To create a single sandbox, all you need is the mysql package that you want install and the make_sandbox command:

[root@localhost ~]# make_sandbox mysql-5.6.17-linux-glibc2.5-i686.tar.gz 
unpacking /root/mysql-5.6.17-linux-glibc2.5-i686.tar.gz
Executing low_level_make_sandbox --basedir=/root/5.6.17 \
	--sandbox_directory=msb_5_6_17 \
	--install_version=5.6 \
	--sandbox_port=5617 \
	--no_ver_after_name \
	--my_clause=log-error=msandbox.err
    The MySQL Sandbox,  version 3.0.44
    (C) 2006-2013 Giuseppe Maxia
installing with the following parameters:
upper_directory                = /root/sandboxes
sandbox_directory              = msb_5_6_17
sandbox_port                   = 5617
check_port                     = 
no_check_port                  = 
datadir_from                   = script
install_version                = 5.6
basedir                        = /root/5.6.17
tmpdir                         = 
my_file                        = 
operating_system_user          = root
db_user                        = msandbox
remote_access                  = 127.%
bind_address                   = 127.0.0.1
ro_user                        = msandbox_ro
rw_user                        = msandbox_rw
repl_user                      = rsandbox
db_password                    = msandbox
repl_password                  = rsandbox
my_clause                      = log-error=msandbox.err
master                         = 
slaveof                        = 
high_performance               = 
prompt_prefix                  = mysql
prompt_body                    =  [\h] {\u} (\d) > 
force                          = 
no_ver_after_name              = 1
verbose                        = 
load_grants                    = 1
no_load_grants                 = 
no_run                         = 
no_show                        = 
do you agree? ([Y],n) 
loading grants
.. sandbox server started
Your sandbox server was installed in $HOME/sandboxes/msb_5_6_17

To use it you can call the use script inside the sandbox folder:

[root@localhost ~]# $HOME/sandboxes/msb_5_6_17/use
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.6.17 MySQL Community Server (GPL)

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql [localhost] {msandbox} ((none)) > 

You can manage your sandbox by calling the start / stop / restart / status script inside the sandbox folder

CREATING A MASTER SLAVE REPLICATION:

To create a master slave replication topology (by default is set to 1 master and 2 slaves but it can be changed passing the --how_many_nodes parameter) we will use the make_replication_sandbox command:

[root@localhost ~]# make_replication_sandbox mysql-5.6.17-linux-glibc2.5-i686.tar.gz 
installing and starting master
installing slave 1
installing slave 2
starting slave 1
.... sandbox server started
starting slave 2
.. sandbox server started
initializing slave 1
initializing slave 2
replication directory installed in $HOME/sandboxes/rsandbox_mysql-5_6_17

To use it we can call the use script, for replication, the use script will be located inside the nodeN/Master folder:

[root@localhost ~]# #MASTER
[root@localhost ~]# /root/sandboxes/rsandbox_mysql-5_6_17/master/use 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 5.6.17-log MySQL Community Server (GPL)

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

master [localhost] {msandbox} ((none)) > ^DBye
[root@localhost ~]# #SLAVE 1
[root@localhost ~]# /root/sandboxes/rsandbox_mysql-5_6_17/node1/use 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.6.17-log MySQL Community Server (GPL)

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

slave1 [localhost] {msandbox} ((none)) > ^DBye
[root@localhost ~]# #SLAVE 2
[root@localhost ~]# /root/sandboxes/rsandbox_mysql-5_6_17/node2/use 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.6.17-log MySQL Community Server (GPL)

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

slave2 [localhost] {msandbox} ((none)) > 

On replication sandbox, you can manage the individual sandbox by calling the start / stop / restart / status script inside the node / master folder or you can call the scripts ending with _all located on the sandbox folder (start_all / stop_all / restart_all / status_all).

CREATING A MULTI MASTER REPLICATION:

To create a multi-master sandbox we will use the make_replication_sandbox with --master_master option:

[root@localhost ~]# make_replication_sandbox --master_master mysql-5.6.17-linux-glibc2.5-i686.tar.gz
installing node 1
installing node 2
# server: 1: 
# server: 2: 
# server: 1: 
# server: 2: 
Circular replication activated
group directory installed in $HOME/sandboxes/rcsandbox_mysql-5_6_17

That is it, you can find more information using the help parameter on make_multiple_custom_sandbox make_multiple_sandbox make_replication_sandbox make_sandbox make_sandbox_from_installed and make_sandbox_from_source

Multi-Source Replication with MySQL 5.7 – example

Complementing this previous post, today we are going to configure 1 slave receiving updates from 2 master with Multi-source replication.
As mention before, this feature is only available on labs.mysql.com.

To configure it, is very simple, we are going to nees 2 masters with GTID enabled (see this post to know how to configure) and a slave with crash save options enabled.

Master 1 e 2:

gtid-mode=on
enforce-gtid-consistency

Slave

master_info_repository=TABLE
relay_log_info_repository=TABLE
gtid-mode=on
enforce-gtid-consistency

Let’s first create our replication user:

master1 [localhost] {msandbox} ((none)) > GRANT REPLICATION SLAVE ON *.* TO 'slave_user'@'127.0.0.1' IDENTIFIED BY '123';
master2 [localhost] {msandbox} ((none)) > GRANT REPLICATION SLAVE ON *.* TO 'slave_user'@'127.0.0.1' IDENTIFIED BY '123';

Now we are going to configure our slave normally, there is a new option named FOR CHANEL, that will identify which master are we connecting to:

slave [localhost] {msandbox} ((none)) > CHANGE MASTER TO MASTER_HOST="127.0.0.1", MASTER_USER="slave_user", MASTER_PASSWORD="123", MASTER_PORT=7773 FOR CHANNEL="channel1";
slave [localhost] {msandbox} ((none)) > CHANGE MASTER TO MASTER_HOST="127.0.0.1", MASTER_USER="slave_user", MASTER_PASSWORD="123", MASTER_PORT=7774 FOR CHANNEL="channel2";

Now, we just need to star the replication:

slave [localhost] {msandbox} ((none)) > START SLAVE FOR ALL CHANNELS;

Let’s insert some data in both master to see if we can retrieve it on our slave:

master1 [localhost] {msandbox} ((none)) > CREATE TABLE test.tst1 (ID INT);
Query OK, 0 rows affected (0.12 sec)

master1 [localhost] {msandbox} ((none)) > INSERT INTO test.tst1 SET ID=1;
Query OK, 1 row affected (0.01 sec)

master2 [localhost] {msandbox} ((none)) >  CREATE TABLE test.tst2 (ID INT);
Query OK, 0 rows affected (0.06 sec)

master2 [localhost] {msandbox} ((none)) > INSERT INTO test.tst2 SET ID=2;
Query OK, 1 row affected (0.01 sec)

slave [localhost] {msandbox} ((none)) > USE test;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
slave [localhost] {msandbox} (test) > SHOW TABLES;
+----------------+
| Tables_in_test |
+----------------+
| tst1           |
| tst2           |
+----------------+
2 rows in set (0.00 sec)

slave [localhost] {msandbox} (test) > SELECT * FROM tst1;
+------+
| ID   |
+------+
|    1 |
+------+
1 row in set (0.00 sec)

slave [localhost] {msandbox} (test) > SELECT * FROM tst2;
+------+
| ID   |
+------+
|    2 |
+------+
1 row in set (0.00 sec)

Some useful commands:

START | STOP SLAVE [SQL_THREAD | IO_THREAD] FOR CHANNEL=”channel name";
START | STOP SLAVE [SQL_THREAD | IO_THREAD] FOR ALL CHANNELS;
SHOW SLAVE STATUS FOR CHANNEL='channel name'\G
FLUSH RELAY LOGS FOR CHANNEL="channel name";
RESET SLAVE FOR CHANNEL="channel name";

That’s it, we now have our slave receiving updates from multiple masters with Multi-source replication.

MySQL Multi Source Replication

Last week, durring MySQL Connect, MySQL 5.7.2 DMR was launched, one of the new functionality is the multi source replication. At the moment, MySQL can have only one master per slave (you can archive multi source replication via some hacks, but like the name says, it’s a hack).

See how to configure here

To clarify, there is a difference between multi-master replication and multi source replication, see the bellow pictures to understand the difference:

MySQL Multi Master Replication

MySQL Multi Master Replication


Multi Master Replication – In the above picture, we have 2 master’s and 1 slave, where, master 1 is master of master 2, master 2 is master of master 1 and also of slave, in order to slave receive updates from master 1, all this updates must past to master 2 to later one be replied to slave.
MySQL Multi Source Replication

MySQL Multi Source Replication


Multi Source Replication – In the above picture, we have 2 master’s and 1 slave, master 1 is only master of slave, and master 2 is only master of slave. The slave receive updates from both master’s directly.

In the next post, I’ll explain how to configure 1 slave and 2 masters in multi source replication.
The test version can be downloades via labs.mysql.com, go there, download and try for yourself.
Remember, this is a test version, so, don’t use in production !!!

Why Does MySQL Replication Delays?

These days I’ve answer some questions about replication lag, and I realized that most of people does not correctly understand how this process works internally on MySQL, and why does delays happen:

See the bellow image, it represents asynchronous replication on MySQL, I highly recommend you to read my other post:

“How Does MySQL Replication Works?”

How replication works

How you can see, there is a big difference related to the entry point of data on master and slave, while the master has multiple simultaneously threads inserting/updating/deleting data, on the slave is just a single one responsible for deal with all these transactions

Let’s imagine that one transaction (an UPDATE for example) took 50 seconds to be applied on the master, during this time, others threads executed queries on the master, what is gonna happen when the slave receive and execute this transaction? yes, you are right, DELAY, all other pending transaction and the ones which got inserted while the slave is applying this UPDATE will need to wait until it finish to be applied.

If you use MySQL from version 5.6.3 and have your data partitioned per database, you can minimize this “bottleneck” using slave-parallel-workers, with this option you can config the number of SQL_THREAD'S to execute simultaneously transaction since they are in different databases.

How Does MySQL Replication Works?

See the bellow image, it represents how asynchronous replication works on MySQL
How replication works

Bearing in mind the number on the image, let’s see how the process works:

  • Item 1 in the image represents the clients executing queries on master, note that the master is capable to handle multiple simultaneous connections (it can be configurable by max_connections variable). 
  • Master process these queries, and save it to his binary log(item number 2 in the image), then it can later on be replied on the slave.
  • The slave has 2 threads reubuntu mount ext4 partitionsponsible to deal with replication :

    • IO_THREAD – is responsible to connect to the Master, ask for new transaction (item number 3 in the image) and save them to his own log (relay log, item number 4 in the image).

    • SQL_THREAD – is responsible for read all new transaction from relay log(item number 5 in the image), and apply them to the database server(item number 6 in the image) .

Got a packet bigger than ‘slave_max_allowed_packet’ bytes and binlog_format = STATEMENT | MIXED

Got a packet bigger than ‘slave_max_allowed_packet’ bytes and binlog_format=STATEMENT|MIXED

Since version 5.1.64 MySQL introduces a new variable named slave_max_allowed_packet, which was introduced to allow large updates using row-based replication do not cause replication to fail when exceeded max_allowed_packet.

The problem is if you have you replication using binlog_format=STATEMENT or binlog_format=MIXED it ignores this option and use as limit for queries what is on max_allowed_packet variable but still reporting on slave_max_allowed_packet causing the IO_THREAD to report the wrong message.

Solution:
Run the follow query on master:

master> SHOW VARIABLES LIKE 'binlog_format';

If it return STATEMENT or MIXED, you need to change the value for max_allowed_packet, a good option if possible is to have this variable equally configured on master and slave.

http://bugs.mysql.com/bug.php?id=68490

http://bugs.mysql.com/bug.php?id=69104

MySQL 5.6 Replication with GTID – Global Transaction ID

Hi guys, Early February Oracle released the new version of MySQL named 5.6, one of the enhancements is the GTID (Global Transaction ID)

GTID is an unique identifier which will be added at each transaction, and will be very useful on the slave. remember before we needed to set MASTER_LOG_FILE and MASTER_LOG_POS, now we don’t need them anymore.

Let’s see some new variables which we need to add to our cnf file:
gtid-mode : It will enable GTID, in order to this function work, we need to turn on log-bin and log-slave-updates
enforce-gtid-consistency : It will guarantee that only allowed command will be executed ( more information here)

Basicly, is only this what we need to enable GTID, for this tutorial I will use 2 virtual machines, black (master – 192.168.1.110) and white (slave – 192.168.1.111), see bellow my cnf file:

black.cnf

[mysqld]
...
binlog-format=MIXED
log-bin
log-slave-updates=true
gtid-mode=on 
enforce-gtid-consistency=true 
master-info-repository=TABLE
relay-log-info-repository=TABLE
sync-master-info=1
binlog-checksum=CRC32
master-verify-checksum=1
server-id=1
report-host=black

white.cnf

[mysqld]
...
binlog-format=MIXED
log-slave-updates=true
log-bin
gtid-mode=on 
enforce-gtid-consistency=true 
master-info-repository=TABLE
relay-log-info-repository=TABLE
sync-master-info=1
slave-parallel-workers=2
binlog-checksum=CRC32
master-verify-checksum=1
slave-sql-verify-checksum=1
binlog-rows-query-log_events=1
server-id=2
report-host=white

Next steep, we need to create the replication user on master (black):

GRANT REPLICATION SLAVE ON *.* TO replication@192.168.1.111 IDENTIFIED BY 'reppwd';
FLUSH PRIVILEGES;

In case you serve already has data, you can follow this post to create a backup from your master, note that now when we raw the SHOW MASTER STATUS; we see a new field named Executed_Gtid_Set, and then restore the backup on slave

Let’s start the replication, the very good stuff in here is that we don’t need to worry about the binary log and position anymore, is just simple as that with GTID:

CHANGE MASTER TO MASTER_HOST='192.168.1.110', MASTER_USER='replication', MASTER_PASSWORD='reppwd', MASTER_AUTO_POSITION=1;
START SLAVE;

At this point, you should have your replication running with GTID, lets see :

white>show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.1.110
                  Master_User: replication
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: black-bin.000002
          Read_Master_Log_Pos: 936
               Relay_Log_File: white-relay-bin.000003
                Relay_Log_Pos: 1146
        Relay_Master_Log_File: black-bin.000002
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB: 
          Replicate_Ignore_DB: 
           Replicate_Do_Table: 
       Replicate_Ignore_Table: 
      Replicate_Wild_Do_Table: 
  Replicate_Wild_Ignore_Table: 
                   Last_Errno: 0
                   Last_Error: 
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 936
              Relay_Log_Space: 1560
              Until_Condition: None
               Until_Log_File: 
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File: 
           Master_SSL_CA_Path: 
              Master_SSL_Cert: 
            Master_SSL_Cipher: 
               Master_SSL_Key: 
        Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error: 
               Last_SQL_Errno: 0
               Last_SQL_Error: 
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 1
                  Master_UUID: 2671c08b-7cf0-11e2-ac39-00163ebee7c2
             Master_Info_File: mysql.slave_master_info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it
           Master_Retry_Count: 86400
                  Master_Bind: 
      Last_IO_Error_Timestamp: 
     Last_SQL_Error_Timestamp: 
               Master_SSL_Crl: 
           Master_SSL_Crlpath: 
           Retrieved_Gtid_Set: 2671c08b-7cf0-11e2-ac39-00163ebee7c2:1-4
            Executed_Gtid_Set: 2671c08b-7cf0-11e2-ac39-00163ebee7c2:1-4
                Auto_Position: 1
1 row in set (0.00 sec)

That Retrieved_Gtid_Set and Executed_Gtid_Set displays the transaction that we read from master, and the transaction that we already executed.

Let’s check if the commands executed on master are replied on slave:

black> CREATE DATABASE gtid_test;
Query OK, 1 row affected (0.00 sec)

black> use gtid_test;
Database changed
black> CREATE TABLE test (id INT NOT NULL PRIMARY KEY);
Query OK, 0 rows affected (0.00 sec)

black> INSERT INTO test (id) VALUES (1), (2), (3), (4), (5);
Query OK, 5 rows affected (0.00 sec)
Records: 5  Duplicates: 0  Warnings: 0

black> 

Now let’s check it on slave:

white> USE gtid_test;
Database changed
white> SELECT * FROM test;
+----+
| id |
+----+
|  1 |
|  2 |
|  3 |
|  4 |
|  5 |
+----+
5 rows in set (0.00 sec)

white>

Done, we have our replication running with Global Transaction ID (GTID)

MySQL Replication with SSL

Hi folks, let’s continue talk about replication, you can see the basics in this other post

First of all, lets create the ssl certificates, go to the master server:
Create CA certificate:

openssl genrsa 2048 > ca-key.pem
openssl req -new -x509 -nodes -days 1000 -key ca-key.pem > ca-cert.pem

Create server certificate:

openssl req -newkey rsa:2048 -days 1000 -nodes -keyout server-key.pem > server-req.pem
openssl x509 -req -in server-req.pem -days 1000 -CA ca-cert.pem -CAkey ca-key.pem -set_serial 01 > server-cert.pem

Create client certificate:

openssl req -newkey rsa:2048 -days 1000 -nodes -keyout client-key.pem > client-req.pem
openssl x509 -req -in client-req.pem -days 1000 -CA ca-cert.pem -CAkey ca-key.pem -set_serial 01 > client-cert.pem

copy ca-cert.pem, client-req.pem, client-cert.pem to slave server

Adjust the cnf file:

ssl
ssl-ca=/etc/mysql/sslcerts/ca-cert.pem
ssl-cert=/etc/mysql/sslcerts/server-cert.pem
ssl-key=/etc/mysql/sslcerts/server-key.pem

Make sure you restart the MySQL service, and check if the ssl is enabled

mysql> SHOW VARIABLES LIKE '%ssl%';
+---------------+-------------------------------------+
| Variable_name | Value                               |
+---------------+-------------------------------------+
| have_openssl  | YES                                 |
| have_ssl      | YES                                 |
| ssl_ca        | /etc/mysql/sslcerts/ca-cert.pem     |
| ssl_capath    |                                     |
| ssl_cert      | /etc/mysql/sslcerts/server-cert.pem |
| ssl_cipher    |                                     |
| ssl_key       | /etc/mysql/sslcerts/server-KEY.pem  |
+---------------+-------------------------------------+
7 rows IN SET (0.00 sec)

Then, we will need a replication user, and we will specify that this user require ssl:

GRANT REPLICATION SLAVE ON *.* TO 'user'@'178.77.90.38' IDENTIFIED BY 'PASSWORD' REQUIRE SSL;
FLUSH PRIVILEGES;

Ok, we have finish your work on master, let’s work on slave server:

Adjust the cnf file:

ssl
ssl-ca=/etc/mysql/sslcerts/ca-cert.pem
ssl-cert=/etc/mysql/sslcerts/client-cert.pem
ssl-key=/etc/mysql/sslcerts/client-key.pem

Let’s check if is everythink ok with ssl

mysql> SHOW VARIABLES LIKE '%ssl%';
+---------------+-------------------------------------+
| Variable_name | Value                               |
+---------------+-------------------------------------+
| have_openssl  | YES                                 |
| have_ssl      | YES                                 |
| ssl_ca        | /etc/mysql/sslcerts/ca-cert.pem     |
| ssl_capath    |                                     |
| ssl_cert      | /etc/mysql/sslcerts/client-cert.pem |
| ssl_cipher    |                                     |
| ssl_key       | /etc/mysql/sslcerts/client-KEY.pem  |
+---------------+-------------------------------------+
7 rows IN SET (0.00 sec)

Finally, Start the replica:

CHANGE MASTER TO MASTER_HOST='xxxxxx', MASTER_USER='user', MASTER_PASSWORD='PASSWORD', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=0, MASTER_SSL=1, MASTER_SSL_CA = '/etc/mysql/sslcerts/ca-cert.pem', MASTER_SSL_CERT = '/etc/mysql/sslcerts/client-cert.pem', MASTER_SSL_KEY = '/etc/mysql/sslcerts/client-key.pem';
START SLAVE;

MySQL replication – Master – Slave

To explain the replication, we will use the article Installing MySQL 5.5 Part 2 – Multiple instances with mysqld_multi because we will need 2 MySQL’s running on our server

Let’s activate the binary logs on our server, creating a file named my_rep.cnf with the follow content:

[mysqld_multi]
mysqld = /mysql/mysql/bin/mysqld_safe
mysqladmin = /mysql/mysql/bin/mysqladmin
[mysqld1]
port = 3306
datadir = /mysql/3306/data
socket = /mysql/3306/mysql.sock
log-error = /mysql/3306/logs/mysqld.log
pid-file = /mysql/3306/mysqld.pid
server_id = 1
#LOGS
log-bin = /mysql/3306/logs/server1_bin.log
log-bin-index = /mysql/3306/logs/server1_log-bin.index
expire_logs_days = 7
binlog-format = MIXED
[mysqld2]
port = 3307
datadir = /mysql/3307/data
socket = /mysql/3307/mysql.sock
log-error = /mysql/3307/logs/mysqld.log
pid-file = /mysql/3307/mysqld.pid
server_id = 2
#LOGS
relay-log = /mysql/3307/logs/server2.relay_log
relay-log-index = /mysql/3307/logs/server2.relay_log_index
expire_logs_days = 7

Done this, let’s start the MySQL service like our article:

cd /mysql/mysql
mysqld_multi --defaults-file=/mysql/my_rep.cnf start

Now, we will connect to server 3306 and create a new user named ‘replication’ with password ‘replication’ and rights to replication.

mysql -u user -p -h 127.0.0.1
mysql> GRANT REPLICATION SLAVE ON *.* TO replication@127.0.0.1 IDENTIFIED BY 'replication';
mysql> FLUSH PRIVILEGES;

Now we need to connect on our slave server and run a start command to start our replication:

mysql -u usuario -p -h 127.0.0.1 --port 3307
mysql> CHANGE MASTER TO MASTER_HOST = '127.0.0.1', MASTER_USER = 'replication', MASTER_PASSWORD = 'replication', MASTER_PORT = 3306, MASTER_LOG_FILE = 'server1_bin.000001', MASTER_LOG_POS = 0;
mysql> START SLAVE;

Let’s explain the CHANGE MASTER TO command:

MASTER_USER = user which will connect to master server
MASTER_PASSWORD = user password which will connect to master server
MASTER_PORT = the mysql master server port
MASTER_LOG_FILE = binary log file name (we set it to server1_bin.log on .cnf file, like we can see, MySQL create file with numeric index which increase each time which server is restarted or exceed the limit set on our configuration by max_binlog_size key which by default is 1GB
MASTER_LOG_POS = the position which the slave will start to search inside the binlog

And how to monitor the replication??? Simple with the command

SHOW SLAVE STATUS;

The replication works with 2 threads:

Slave_IO = Is the thread responsible to get all sql commands from master and save them at the slave disc
Slave_SQL = Is the thread responsible to run the commands which Slave_IO get from master server

Now, I will explain 5 important status from

SHOW SLAVE STATUS;

Slave_IO_Running = Tell us if the IO thread is running, we need to see a Yes on this line
Slave_SQL_Running = Tell us if the SQL thread is running, we need to see a Yes on this line
Seconds_Behind_Master = Tell us if our slave is delayed in relation to our master, here we need to see a 0(zero)
Last_IO_Error = In case we have a problem with IO thread, this line will show us the problem
Last_SQL_Error = In case we have a problem with SQL thread, this line will show us the problem

And is it, now he have a Master server replication their data to a SLAVE server.

To see more details about replication on MySQL, please read MySQL Documentation