MySQL en cluster
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Pré-requis
L'installation a été faite sur des debian etch stables. Pour faire un cluster MySQL correct il est nécessaire de posséder un minimum de 3 serveurs. Le premier servira de manager et les deux autres de noeuds mysql ou de stockage.
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Installation du manager
Installer les paquets mysql:
sudo aptitude install mysql-server
Empêcher mysql de se lancer au démarrage:
sudo update-rc.d -f mysql remove
Empêcher le serveur de noeud aussi:
sudo update-rc.d -f mysql-ndbd
Configurer le manager:
sudo cp /usr/share/doc/mysql-server-5.0/examples/ndb_mgmd.cnf /etc/mysql vi /etc/mysql/ndb_mgmd.cnf
[NDBD DEFAULT] NoOfReplicas=3 # Nombre de noeuds NDB DataMemory=10MB IndexMemory=25MB MaxNoOfTables=256 MaxNoOfOrderedIndexes=256 MaxNoOfUniqueHashIndexes=128 [MYSQLD DEFAULT] [NDB_MGMD DEFAULT] [TCP DEFAULT] [NDB_MGMD] Id=1 # Le manager lui même HostName=10.0.0.252 # Avec son adresse ip [NDBD] Id=2 # Un premier noeud HostName=10.0.0.224 DataDir= /var/lib/mysql-cluster [NDBD] Id=3 # Le deuxième noeud HostName=10.0.0.225 DataDir=/var/lib/mysql-cluster [NDBD] Id=4 # Le troisième noeud HostName=10.0.0.226 DataDir=/var/lib/mysql-cluster [MYSQLD] Id=5 # Le premier noeud sql HostName=10.0.0.224 [MYSQLD] Id=6 # Le deuxième noeud sql HostName=10.0.0.225 [MYSQLD] Id=7 # Le troisième noeud sql HostName=192.168.1.108
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Installation d'un noeud
Comme pour le manager, installer les paquets mysql:
sudo aptitude install mysql-server
Configurer le noeud:
sudo vi /etc/mysql/my.cnf
# # The MySQL database server configuration file. # # You can copy this to one of: # - "/etc/mysql/my.cnf" to set global options, # - "~/.my.cnf" to set user-specific options. # # One can use all long options that the program supports. # Run program with --help to get a list of available options and with # --print-defaults to see which it would actually understand and use. # # For explanations see # http://dev.mysql.com/doc/mysql/en/server-system-variables.html # This will be passed to all mysql clients # It has been reported that passwords should be enclosed with ticks/quotes # escpecially if they contain "#" chars... # Remember to edit /etc/mysql/debian.cnf when changing the socket location. [client] port = 3306 socket = /var/run/mysqld/mysqld.sock # Here is entries for some specific programs # The following values assume you have at least 32M ram # This was formally known as [safe_mysqld]. Both versions are currently parsed. [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] # # * Basic Settings # user = mysql pid-file = /var/run/mysqld/mysqld.pid socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp language = /usr/share/mysql/english skip-external-locking ndbcluster ndb-connectstring = 10.0.0.252 # # Instead of skip-networking the default is now to listen only on # localhost which is more compatible and is not less secure. bind-address = 10.0.0.224 # # * Fine Tuning # key_buffer = 16M max_allowed_packet = 16M thread_stack = 128K thread_cache_size = 8 #max_connections = 100 #table_cache = 64 #thread_concurrency = 10 # # * Query Cache Configuration # query_cache_limit = 1M query_cache_size = 16M # # * Logging and Replication # # Both location gets rotated by the cronjob. # Be aware that this log type is a performance killer. #log = /var/log/mysql/mysql.log # # Error logging goes to syslog. This is a Debian improvement :) # # Here you can see queries with especially long duration #log_slow_queries = /var/log/mysql/mysql-slow.log #long_query_time = 2 #log-queries-not-using-indexes # # The following can be used as easy to replay backup logs or for replication. #server-id = 1 log_bin = /var/log/mysql/mysql-bin.log # WARNING: Using expire_logs_days without bin_log crashes the server! See README.Debian! expire_logs_days = 10 max_binlog_size = 100M #binlog_do_db = include_database_name #binlog_ignore_db = include_database_name # # * BerkeleyDB # # Using BerkeleyDB is now discouraged as its support will cease in 5.1.12. skip-bdb # # * InnoDB # # InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/. # Read the manual for more InnoDB related options. There are many! # You might want to disable InnoDB to shrink the mysqld process by circa 100MB. #skip-innodb # # * Security Features # # Read the manual, too, if you want chroot! # chroot = /var/lib/mysql/ # # For generating SSL certificates I recommend the OpenSSL GUI "tinyca". # # ssl-ca=/etc/mysql/cacert.pem # ssl-cert=/etc/mysql/server-cert.pem # ssl-key=/etc/mysql/server-key.pem [mysqldump] quick quote-names max_allowed_packet = 16M [mysql] #no-auto-rehash # faster start of mysql but no tab completition [isamchk] key_buffer = 16M # # * NDB Cluster # # See /usr/share/doc/mysql-server-*/README.Debian for more information. # # The following configuration is read by the NDB Data Nodes (ndbd processes) # not from the NDB Management Nodes (ndb_mgmd processes). # [MYSQL_CLUSTER] ndb-connectstring = 10.0.0.252 # Read the manual for more InnoDB related options. There are many! # You might want to disable InnoDB to shrink the mysqld process by circa 100MB. #skip-innodb # # * Security Features # # Read the manual, too, if you want chroot! # chroot = /var/lib/mysql/ # # For generating SSL certificates I recommend the OpenSSL GUI "tinyca". # # ssl-ca=/etc/mysql/cacert.pem # ssl-cert=/etc/mysql/server-cert.pem # ssl-key=/etc/mysql/server-key.pem [mysqldump] quick quote-names max_allowed_packet = 16M [mysql] #no-auto-rehash # faster start of mysql but no tab completition [isamchk] key_buffer = 16M # # * NDB Cluster # # See /usr/share/doc/mysql-server-*/README.Debian for more information. # # The following configuration is read by the NDB Data Nodes (ndbd processes) # not from the NDB Management Nodes (ndb_mgmd processes). # [MYSQL_CLUSTER] ndb-connectstring = 10.0.0.252 # # * IMPORTANT: Additional settings that can override those from this file! # !includedir /etc/mysql/conf.d/
Les sections qui nous intéressent sont mysqld et mysql_cluster:
[mysqld] # # * Basic Settings # user = mysql pid-file = /var/run/mysqld/mysqld.pid socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp language = /usr/share/mysql/english skip-external-locking ndbcluster ndb-connectstring = 10.0.0.252
Notez les deux dernières lignes, ndb-connectstring correspondant à l'ip du manager. Et:
[MYSQL_CLUSTER] ndb-connectstring = 10.0.0.252
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Démarrage du cluster
Pour démarrer le cluster, commencer par lancer le manager:
sudo /etc/init.d/mysql-ndb-mgm start
Puis démarrez les noeuds, si c'est le premier démarrage de ce noeud:
sudo /etc/init.d/mysql-ndb start-initial
sinon:
sudo /etc/init.d/mysql-ndb start
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Arrêt du cluster
Se connecter sur le manager et utiliser ndb_mgm:
sudo ndb_mgm shutdown
ATTENTION: ne jamais couper le manager avant les noeuds, vous risquez de perdre des données !
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Vérification du cluster
Pour vérifier l'état du cluster, se connecter sur le manager puis lancer ndb_mgm:
sudo ndb_mgm show
et là vous devriez avoir une liste du type:
-- NDB Cluster -- Management Client -- ndb_mgm> show Connected to Management Server at: 10.0.0.252:1186 Cluster Configuration --------------------- [ndbd(NDB)] 1 node(s) id=2 @10.0.0.224 (Version: 5.0.32, Nodegroup: 0, Master) [ndb_mgmd(MGM)] 1 node(s) id=1 @10.0.0.252 (Version: 5.0.32) [mysqld(API)] 1 node(s) id=5 @10.0.0.224 (Version: 5.0.32)
Si un noeud n'est pas connecté, celui-ci est signalé dans la liste:
Cluster Configuration --------------------- [ndbd(NDB)] 1 node(s) id=2 (not connected, accepting connect from 10.0.0.224) [ndb_mgmd(MGM)] 1 node(s) id=1 @10.0.0.252 (Version: 5.0.32) [mysqld(API)] 1 node(s) id=5 (not connected, accepting connect from 10.0.0.224)
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Tests avec une base
Se connecter sur un des noeuds, jamais sur le manager:
mysql -h 10.0.0.252 -u root -p create database tests create table toto (id int) ENGINE=NDBCLUSTER
Le cluster fonctionne en spécifiant le moteur utilisé pour une table. Pour modifier une table existante:
alter table toto ENGINE=NDBCLUSTER
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Forcer l'utilisation d'une table en cluster
Pour éviter de faire des alter table à gogo, il est possible de spécifier à mysql que le moteur par défaut est le cluster.
sudo vi /etc/mysql/my.cnf
Rajouter dans la section mysqld:
[mysqld] default-table-type=NDBCLUSTER
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Erreurs courantes
- Si vous voyez une erreur 2350 sur le manager lors de la tentative de connection d'un noeud, c'est que celui-ci n'est pas initialisé correctement:
sudo /etc/init.d/mysql-ndb start-initial
sur le noeud posant problème devrait corriger la situation.
- Les clusters mysql ne sont pas sécurisés
- Les clusters mysql ont besoin de beaucoup de bande passante, une carte 100mb est le minimum pour avoir des performances correctes
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Liens
Un Howto un peu vieux mais bien écrit (en anglais):
La doc officielle:
Un autre Howto un peu vieux aussi (en français):
MysqlCluster et la mémoire:
