====== Installation Guide ====== ** Note: this guide is a draft, feel free to make changes if you see anything that can be improved, expanded on or corrected ** This installation guide describes a installation of MMM 2 (without the MMM tools) based on Debian Lenny (5.0) A basic installation contains at least 2 database servers and 1 monitoring server. In this guide, I used 5 servers with Debian Lenny (5.0) ^ function ^ ip ^ hostname ^ server id ^ | monitoring host | 192.168.0.10 | mon | - | | master 1 | 192.168.0.11 | db1 | 1 | | master 2 | 192.168.0.12 | db2 | 2 | | slave 1 | 192.168.0.13 | db3 | 3 | | slave 2 | 192.168.0.14 | db4 | 4 | I used the following //virtual// IPs. They will be distributed across the hosts by MMM. ^ ip ^ role ^ description ^ | 192.168.0.100 | writer | Your application should connect to this IP for write queries. | | 192.168.0.101 | reader | Your application should connect to one of these four IPs for read queries | | 192.168.0.102 | reader | ::: | | 192.168.0.103 | reader | ::: | | 192.168.0.104 | reader | ::: | ===== Basic configuration of master 1 ===== First we install MySQL on all hosts: aptitude install mysql-server Then we edit the configuration file /etc/mysql/my.cnf and add the following lines - be sure to use different server ids for all hosts: server_id = 1 log_bin = /var/log/mysql/mysql-bin.log log_bin_index = /var/log/mysql/mysql-bin.log.index relay_log = /var/log/mysql/mysql-relay-bin relay_log_index = /var/log/mysql/mysql-relay-bin.index expire_logs_days = 10 max_binlog_size = 100M log_slave_updates = 1 read_only = 1 Then remove the following entry: bind-address = 127.0.0.1 Afterwards we need to restart MySQL for our changes to take effect: /etc/init.d/mysql restart ===== Create users ===== Now we can create the required users. We'll need 3 different users: ^ function ^ description ^ privileges ^ | monitor user | used by the mmm monitor to check the health of the MySQL servers | REPLICATION CLIENT | | agent user | used by the mmm agent to change read-only mode, replication master, etc. | SUPER, REPLICATION CLIENT, PROCESS | | relication user | used for replication | REPLICATION SLAVE | GRANT REPLICATION CLIENT ON *.* TO 'mmm_monitor'@'192.168.0.%' IDENTIFIED BY 'monitor_password'; GRANT SUPER, REPLICATION CLIENT, PROCESS ON *.* TO 'mmm_agent'@'192.168.0.%' IDENTIFIED BY 'agent_password'; GRANT REPLICATION SLAVE ON *.* TO 'replication'@'192.168.0.%' IDENTIFIED BY 'replication_password'; **Note:** We could be more restrictive here regarding the hosts from which the users are allowed to connect: mmm_monitor is used from 192.168.0.10. mmm_agent and replication are used from 192.168.0.11 - 192.168.0.14. ===== Synchronisation of data between both databases ===== I'll assume that db1 contains the correct data. If you have an empty database, you still have to syncronize the accounts we have just created. First make sure that no one is altering the data while we create a backup. (db1) mysql> FLUSH TABLES WITH READ LOCK; Then get the current position in the binary-log. We will need this values when we setup the replication on db2, db3 and db4. (db1) mysql> SHOW MASTER STATUS; +------------------+----------+--------------+------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | +------------------+----------+--------------+------------------+ | mysql-bin.000002 | 374 | | | +------------------+----------+--------------+------------------+ 1 row in set (0.00 sec) **DON'T CLOSE this mysql-shell.** If you close it, the database lock will be removed. Open a second console and type: db1$ mysqldump -u root -p --all-databases > /tmp/database-backup.sql Now we can remove the database-lock. Go to the first shell: (db1) mysql> UNLOCK TABLES; Copy the database backup to db2, db3 and db4. db1$ scp /tmp/database-backup.sql @192.168.0.12:/tmp db1$ scp /tmp/database-backup.sql @192.168.0.13:/tmp db1$ scp /tmp/database-backup.sql @192.168.0.14:/tmp Then import this into db2, db3 and db4: db2$ mysql -u root -p < /tmp/database-backup.sql db3$ mysql -u root -p < /tmp/database-backup.sql db4$ mysql -u root -p < /tmp/database-backup.sql Then flush the privileges on db2, db3 and db4. We have altered the user-table and mysql has to reread this table. (db2) mysql> FLUSH PRIVILEGES; (db3) mysql> FLUSH PRIVILEGES; (db4) mysql> FLUSH PRIVILEGES; On debian and ubuntu, copy the passwords in /etc/mysql/debian.cnf from db1 to db2, db3 and db4. This password is used for starting and stopping mysql. Both databases now contain the same data. We now can setup replication to keep it that way. ===== Setup replication ===== Configure replication on db2, db3 and db4 with the following commands: (db2) mysql> CHANGE MASTER TO master_host='192.168.0.11', master_port=3306, master_user='replication', master_password='replication_password', master_log_file='', master_log_pos=; (db3) mysql> CHANGE MASTER TO master_host='192.168.0.11', master_port=3306, master_user='replication', master_password='replication_password', master_log_file='', master_log_pos=; (db4) mysql> CHANGE MASTER TO master_host='192.168.0.11', master_port=3306, master_user='replication', master_password='replication_password', master_log_file='', master_log_pos=; Please insert the values return by “show master status” on db1 at the and tags. Start the slave-process on all 3 hosts: (db2) mysql> START SLAVE; (db3) mysql> START SLAVE; (db4) mysql> START SLAVE; Now check if the replication is running correctly on all hosts: (db2) mysql> SHOW SLAVE STATUS\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.0.11 Master_User: replication Master_Port: 3306 Connect_Retry: 60 … (db3) mysql> SHOW SLAVE STATUS\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.0.11 Master_User: replication Master_Port: 3306 Connect_Retry: 60 … (db4) mysql> SHOW SLAVE STATUS\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.0.11 Master_User: replication Master_Port: 3306 Connect_Retry: 60 … Now we have to make db1 replicate from db2. First we have to determine the values for master_log_file and master_log_pos: (db2) mysql> SHOW MASTER STATUS; +------------------+----------+--------------+------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | +------------------+----------+--------------+------------------+ | mysql-bin.000001 | 98 | | | +------------------+----------+--------------+------------------+ 1 row in set (0.00 sec) Now we configure replication on db1 with the following command: (db1) mysql> CHANGE MASTER TO master_host = '192.168.0.12', master_port=3306, master_user='replication', master_password='replication_password', master_log_file='', master_log_pos=; Now insert the values return by “show master status” on db2 at the and tags. Start the slave-process: (db1) mysql> START SLAVE; Now check if the replication is running correctly on db1: (db1) mysql> SHOW SLAVE STATUS\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.0.12 Master_User: Master_Port: 3306 Connect_Retry: 60 … Replication between the nodes should now be complete. Try it by inserting some data into both db1 and db2 and check that the data will appear on all other nodes. ===== Install MMM ===== ==== Create user ==== Optional: Create user that will be the owner of the MMM scripts and configuration files. This will provide an easier method to securely manage the monitor scripts. useradd --comment "MMM Script owner" --shell /sbin/nologin mmmd ==== Monitoring host ==== First install dependencies: aptitude install liblog-log4perl-perl libmailtools-perl liblog-dispatch-perl libclass-singleton-perl libproc-daemon-perl libalgorithm-diff-perl libdbi-perl libdbd-mysql-perl Then fetch the latest mysql-mmm-common*.deb and mysql-mmm-monitor*.deb and install it: dpkg -i mysql-mmm-common_*.deb mysql-mmm-monitor*.deb ==== Database hosts ==== First install dependencies: aptitude install liblog-log4perl-perl libmailtools-perl liblog-dispatch-perl iproute libnet-arp-perl libproc-daemon-perl libalgorithm-diff-perl libdbi-perl libdbd-mysql-perl Then fetch the latest mysql-mmm-common*.deb and mysql-mmm-agent*.deb and install it: dpkg -i mysql-mmm-common_*.deb mysql-mmm-agent_*.deb ==== Configure MMM === All generic configuration-options are grouped in a separate file called /etc/mysql-mmm/mmm_common.conf. This file will be the same on all hosts in the system: active_master_role writer cluster_interface eth0 pid_path /var/run/mmmd_agent.pid bin_path /usr/lib/mysql-mmm/ replication_user replication replication_password replication_password agent_user mmm_agent agent_password agent_password ip 192.168.0.11 mode master peer db2 ip 192.168.0.12 mode master peer db1 ip 192.168.0.13 mode slave ip 192.168.0.14 mode slave hosts db1, db2 ips 192.168.0.100 mode exclusive hosts db1, db2, db3, db4 ips 192.168.0.101, 192.168.0.102, 192.168.0.103, 192.168.0.104 mode balanced Don't forget to copy this file to all other hosts (including the monitoring host). On the database hosts we need to edit /etc/mysql-mmm/mmm_agent.conf. Change "db1" accordingly on the other hosts: include mmm_common.conf this db1 On the monitor host we need to edit /etc/mysql-mmm/mmm_mon.conf: include mmm_common.conf ip 127.0.0.1 pid_path /var/run/mmmd_mon.pid bin_path /usr/lib/mysql-mmm/ status_path /var/lib/misc/mmmd_mon.status ping_ips 192.168.0.1, 192.168.0.11, 192.168.0.12, 192.168.0.13, 192.168.0.14 monitor_user mmm_monitor monitor_password monitor_password debug 0 ping_ips are some ips that are pinged to determine whether the network connection of the monitor is ok. I used my switch (192.168.0.1) and the four database server. ===== Start MMM ===== ==== Start the agents ==== **(On the database hosts)** Edit /etc/default/mysql-mmm-agent to enable the agent: ENABLED=1 Then start it: /etc/init.d/mysql-mmm-agent start ==== Start the monitor ==== **(On the monitoring host)** Edit /etc/default/mysql-mmm-monitor to enable the monitor: ENABLED=1 Then start it: /etc/init.d/mysql-mmm-monitor start Wait some seconds for mmmd_mon to start up. After a few seconds you can use mmm_control to check the status of the cluster: mon$ mmm_control show db1(192.168.0.11) master/AWAITING_RECOVERY. Roles: db2(192.168.0.12) master/AWAITING_RECOVERY. Roles: db3(192.168.0.13) slave/AWAITING_RECOVERY. Roles: db4(192.168.0.14) slave/AWAITING_RECOVERY. Roles: Because its the first startup the monitor does not know our hosts, so it sets all hosts to state AWAITING_RECOVERY and logs a warning message: mon$ tail /var/log/mysql-mmm/mmmd_mon.warn … 2009/10/28 23:15:28 WARN Detected new host 'db1': Setting its initial state to 'AWAITING_RECOVERY'. Use 'mmm_control set_online db1' to switch it online. 2009/10/28 23:15:28 WARN Detected new host 'db2': Setting its initial state to 'AWAITING_RECOVERY'. Use 'mmm_control set_online db2' to switch it online. 2009/10/28 23:15:28 WARN Detected new host 'db3': Setting its initial state to 'AWAITING_RECOVERY'. Use 'mmm_control set_online db3' to switch it online. 2009/10/28 23:15:28 WARN Detected new host 'db4': Setting its initial state to 'AWAITING_RECOVERY'. Use 'mmm_control set_online db4' to switch it online. Now we set or hosts online (db1 first, because the slaves replicate from this host): mon$ mmm_control set_online db1 OK: State of 'db1' changed to ONLINE. Now you can wait some time and check its new roles! mon$ mmm_control set_online db2 OK: State of 'db2' changed to ONLINE. Now you can wait some time and check its new roles! mon$ mmm_control set_online db3 OK: State of 'db3' changed to ONLINE. Now you can wait some time and check its new roles! mon$ mmm_control set_online db4 OK: State of 'db4' changed to ONLINE. Now you can wait some time and check its new roles!