MySQL集群高可用

来源:https://www.cnblogs.com/www233ii/archive/2019/12/03/11978513.html

MySQL高可用 Galera Cluster [toc] Galera Cluster Galera Cluster:集成了Galera插件的MySQL集群,是一種新型的,數據不共用的,高度冗餘的高可用方案,目前Galera Cluster有兩個版本,分別是Percona Xtradb Clust ...


MySQL高可用 Galera Cluster

Galera Cluster

Galera Cluster:集成了Galera插件的MySQL集群,是一種新型的,數據不共用的,高度冗餘的高可用方案,目前Galera Cluster有兩個版本,分別是Percona Xtradb Cluster及MariaDB Cluster,Galera本身是具有多主特性的,即採用multi-master的集群架構,是一個既穩健,又在數據一致性、完整性及高性能方面有出色表現的高可用解決方案

在這裡插入圖片描述

Galera Cluster特點

• 多主架構:真正的多點讀寫的集群,在任何時候讀寫數據,都是最新的

• 同步複製:集群不同節點之間數據同步,沒有延遲,在資料庫掛掉之後,數據不會丟失

• 併發複製:從節點APPLY數據時,支持並行執行,更好的性能

• 故障切換:在出現資料庫故障時,因支持多點寫入,切換容易

• 熱插拔:在服務期間,如果資料庫掛了,只要監控程式發現的夠快,不可服務時間就會非常少。在節點故障期間,節點本身對集群的影響非常小

• 自動節點克隆:在新增節點,或者停機維護時,增量數據或者基礎數據不需要人工手動備份提供,Galera Cluster會自動拉取線上節點數據,最終集群會變為一致

• 對應用透明:集群的維護,對應用程式是透明的
只支持innodb存儲引擎的表

Galera Cluster 缺點

• 由於DDL 需全局驗證通過,則集群性能由集群中最差性能節點決定(一般集群節點配置都是一樣的)

• 新節點加入或延後較大的節點重新加入需全量拷貝數據(SST,State Snapshot Transfer),作為donor( 貢獻者,如: 同步數據時的提供者)的節點在同步過程中無法提供讀寫

• 只支持innodb存儲引擎的表

Galera Cluster工作過程

在這裡插入圖片描述

Galera Cluster官方文檔

http://galeracluster.com/documentation-webpages/galera-documentation.pdf
http://galeracluster.com/documentation-webpages/index.html
https://www.percona.com/doc/percona-xtradb-cluster/LATEST/index.html
https://mariadb.com/kb/en/library/getting-started-with-mariadb-galera-cluster/

Galera Cluster包括兩個組件

• Galera replication library (galera-3)
• WSREP:MySQL extended with the Write Set Replication

WSREP複製實現

  • PXC:Percona XtraDB Cluster,是Percona對Galera的實現
    參考倉庫:
https://mirrors.tuna.tsinghua.edu.cn/percona/release/$releasever/RPMS/$basearch
  • MariaDB Galera Cluster:
    參考倉庫:
https://mirrors.tuna.tsinghua.edu.cn/mariadb/mariadb-5.5.X/yum/centos7-amd64/
註意:兩者都需要至少三個節點,不能安裝mysql server 或 mariadb-server

PXC 原理

在這裡插入圖片描述

PXC最常使用如下4個埠號:

• 3306:資料庫對外服務的埠號
• 4444:請求SST的埠號
• 4567:組成員之間進行溝通的埠號
• 4568:用於傳輸IST的埠號

PXC中涉及到的重要概念和核心參數:

  1. 集群中節點的數量:整個集群中節點數量應該控制在最少3個、最多8個的範圍內。最少3個節點是為了防止出現腦裂現象,因為只有在2個節點下才會出現此現象。腦裂現象的標誌就是輸入任何命令,返回的結果都是unknown command。節點在集群中,會因新節點的加入或故障、同步失效等原因發生狀態的切換。
  2. 節點狀態的變化階段:
    在這裡插入圖片描述
• open:節點啟動成功,嘗試連接到集群時的狀態
• primary:節點已處於集群中,在新節點加入並選取donor進行數據同步時的狀態
• joiner:節點處於等待接收同步文件時的狀態
• joined:節點完成數據同步工作,嘗試保持和集群進度一致時的狀態
• synced:節點正常提供服務時的狀態,表示已經同步完成並和集群進度保持一致
• donor:節點處於為新加入的節點提供全量數據時的狀態  
備註:donor節點就是數據的貢獻者,如果一個新節點加入集群,此時又需要大量數據的SST數據傳輸,就有可能因此而拖垮整個集群的性能,所以在生產環境中,如果數據量較小,還可以使用SST全量數據傳輸,但如果數據量很大就不建議使用這種方式,可以考慮先建立主從關係,然後再加入集群。
  1. 節點的數據傳輸方式:
• SST:State Snapshot Transfer,全量數據傳輸
• IST:Incremental State Transfer,增量數據傳輸 
SST數據傳輸有xtrabackup、mysqldump和rsync三種方式,而增量數據傳輸就只有一種方式xtrabackup,但生產環境中一般數據量較小時,可以使用SST全量數據傳輸,但也只使用xtrabackup方法。
  1. GCache模塊:
在PXC中一個特別重要的模塊,它的核心功能就是為每個節點緩存當前最新的寫集。如果有新節點加入進來,就可以把新數據的增量傳遞給新節點,而不需要再使用SST傳輸方式,這樣可以讓節點更快地加入集群中
  1. 涉及如下參數:
• gcache.size:緩存寫集增量信息的大小,它的預設大小是128MB,通過wsrep_provider_options參數設置,建議調整為2GB~4GB範圍,足夠的空間便於緩存更多的增量信息。
• gcache.mem_size:GCache中記憶體緩存的大小,適度調大可以提高整個集群的性能
• gcache.page_size:如果記憶體不夠用(GCache不足),就直接將寫集寫入磁碟文件中

實戰案例:Percona XtraDB Cluster(PXC 5.7)

  1. 環境準備

    四台主機:

    pxc1:192.168.39.7
    pxc1:192.168.39.27
    pxc1:192.168.39.37
    pxc4:192.168.39.47

       OS版本

    [[email protected] ~]#cat /etc/redhat-release 
    CentOS Linux release 7.6.1810 (Core) 
    關閉防火牆和SELinux,保證時間同步
    註意:如果已經安裝MySQL,必須卸載
  2. 安裝 Percona XtraDB Cluster 5.7
  • 配置yum源
[[email protected] ~]#vim /etc/yum.repos.d/percona_pxc.repo

[percona]
name=percona_repo
baseurl=https://mirrors.tuna.tsinghua.edu.cn/percona/release/$releasever/RPMS/$basearch
enabled=1
gpgcheck=0
  • 其他三台虛擬機也配置yum源
scp /etc/yum.repos.d/percona_pxc.repo 192.168.39.27:/etc/yum.repos.d/
scp /etc/yum.repos.d/percona_pxc.repo 192.168.39.37:/etc/yum.repos.d/
scp /etc/yum.repos.d/percona_pxc.repo 192.168.39.47:/etc/yum.repos.d/
  • 在三個節點都安裝好PXC 5.7
[[email protected] ~]#yum install Percona-XtraDB-Cluster-57 -y
[[email protected] ~]#yum install Percona-XtraDB-Cluster-57 -y
[[email protected] ~]#yum install Percona-XtraDB-Cluster-57 -y
[[email protected] ~]#yum install Percona-XtraDB-Cluster-57 -y
  1. 在各個節點上分別配置mysql及集群配置文件
/etc/my.cnf為主配置文件,當前版本中,其餘的配置文件都放在/etc/percona-xtradb-cluster.conf.d目錄里,包括mysqld.cnf,mysqld_safe.cnf,wsrep.cnf 三個文件
#主配置文件不需要修改
[[email protected] ~]#cat /etc/my.cnf
#
# The Percona XtraDB Cluster 5.7 configuration file.
#
#
# * IMPORTANT: Additional settings that can override those from this file!
#   The files must end with '.cnf', otherwise they'll be ignored.
#   Please make any edits and changes to the appropriate sectional files
#   included below.
#
!includedir /etc/my.cnf.d/
!includedir /etc/percona-xtradb-cluster.conf.d/

[[email protected] ~]#ls /etc/percona-xtradb-cluster.conf.d/  # 查看一下三個文件
mysqld.cnf  mysqld_safe.cnf  wsrep.cnf

#下麵配置文件不需要修改
[[email protected] ~]#cat /etc/percona-xtradb-cluster.conf.d/mysqld.cnf 
# Template my.cnf for PXC
# Edit to your requirements.
[client]
socket=/var/lib/mysql/mysql.sock

[mysqld]
server-id=1   # 建議各個節點不同
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
log-bin   # 建議啟用,非必須項
log_slave_updates
expire_logs_days=7

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

#下麵配置文件不需要修改
[[email protected] ~]#cat /etc/percona-xtradb-cluster.conf.d/mysqld_safe.cnf 
#
# The Percona Server 5.7 configuration file.
#
# 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

[mysqld_safe]
pid-file = /var/run/mysqld/mysqld.pid
socket   = /var/lib/mysql/mysql.sock
nice     = 0

#PXC的配置文件必須修改
[mysqld]
wsrep_provider=/usr/lib64/galera3/libgalera_smm.so
wsrep_cluster_address=gcomm://10.0.0.7,10.0.0.17,10.0.0.27 #三個節點的IP
binlog_format=ROW
default_storage_engine=InnoDB
wsrep_slave_threads= 8
wsrep_log_conflicts
innodb_autoinc_lock_mode=2
wsrep_node_address=10.0.0.7 #各個節點,指定自已的IP
wsrep_cluster_name=pxc-cluster   # 集群名稱
wsrep_node_name=pxc-cluster-node-1 #各個節點,指定自已節點名稱
pxc_strict_mode=ENFORCING
wsrep_sst_method=xtrabackup-v2
wsrep_sst_auth="sstuser:centos7" #取消本行註釋,可以改一個自己的密碼

# 根據以上修改信息所有主機都修改
[[email protected] ~]#vim /etc/percona-xtradb-cluster.conf.d/wsrep.cnf  
[[email protected] ~]#vim /etc/percona-xtradb-cluster.conf.d/wsrep.cnf

[[email protected] ~]#grep -Ev "^#|^$" /etc/percona-xtradb-cluster.conf.d/wsrep.cnf # 通過這個命令查看配置文件
[mysqld]
wsrep_provider=/usr/lib64/galera3/libgalera_smm.so
wsrep_cluster_address=gcomm://192.168.39.7,192.168.39.27,192.168.39.37
binlog_format=ROW
default_storage_engine=InnoDB
wsrep_slave_threads= 8
wsrep_log_conflicts
innodb_autoinc_lock_mode=2
wsrep_node_address=192.168.39.7
wsrep_cluster_name=pxc-cluster
wsrep_node_name=pxc-cluster-node-1
pxc_strict_mode=ENFORCING
wsrep_sst_method=xtrabackup-v2
wsrep_sst_auth="sstuser:centos7"
註意:儘管Galera Cluster不再需要通過binlog的形式進行同步,但還是建議在配置文件中開啟二進位日誌功能,原因是後期如果有新節點需要加入,老節點通過SST全量傳輸的方式向新節點傳輸數據,很可能會拖垮集群性能,所以讓新節點先通過binlog方式完成同步後再加入集群會是一種更好的選擇
  1. 配置文件各項配置意義
    在這裡插入圖片描述
    在這裡插入圖片描述
[[email protected] ~]#ss -ntul
Netid State      Recv-Q Send-Q                                               Local Address:Port                                                              Peer Address:Port              
udp   UNCONN     0      0                                                    192.168.122.1:53                                                                           *:*                  
udp   UNCONN     0      0                                                         *%virbr0:67                                                                           *:*                  
udp   UNCONN     0      0                                                                *:111                                                                          *:*                  
udp   UNCONN     0      0                                                                *:5353                                                                         *:*                  
udp   UNCONN     0      0                                                                *:58153                                                                        *:*                  
udp   UNCONN     0      0                                                                *:812                                                                          *:*                  
udp   UNCONN     0      0                                                               :::111                                                                         :::*                  
udp   UNCONN     0      0                                                               :::812                                                                         :::*                  
tcp   LISTEN     0      128                                                              *:111                                                                          *:*                  
tcp   LISTEN     0      128                                                              *:6000                                                                         *:*                  
tcp   LISTEN     0      5                                                    192.168.122.1:53                                                                           *:*                  
tcp   LISTEN     0      128                                                              *:22                                                                           *:*                  
tcp   LISTEN     0      128                                                      127.0.0.1:631                                                                          *:*                  
tcp   LISTEN     0      128                                                      127.0.0.1:6010                                                                         *:*                  
tcp   LISTEN     0      128                                                             :::111                                                                         :::*                  
tcp   LISTEN     0      128                                                             :::6000                                                                        :::*                  
tcp   LISTEN     0      128                                                             :::22                                                                          :::*                  
tcp   LISTEN     0      128                                                            ::1:631                                                                         :::*                  
tcp   LISTEN     0      128                                                            ::1:6010                                                                        :::*            

#啟動第一人節點(第一個節點啟動和別的節點啟動都不一樣)屬於創建集群的伺服器現在階段可以理解為主伺服器,但是集群做完之後就沒有主從之分了都是主
[[email protected] ~]#systemctl start [email protected]
[[email protected] ~]#ss -ntul  # 以下兩個埠啟動起來就行了 (3306、4567)
。。。。。。。。。。。。。。。。。。。。。。。
Netid  State      Recv-Q Send-Q Local Address:Port               Peer Address:Port              
udp    UNCONN     0      0      192.168.122.1:53                         *:*                  
udp    UNCONN     0      0       *%virbr0:67                         *:*                  
udp    UNCONN     0      0              *:111                        *:*                  
udp    UNCONN     0      0              *:5353                       *:*                  
udp    UNCONN     0      0              *:58153                      *:*                  
udp    UNCONN     0      0              *:812                        *:*                  
udp    UNCONN     0      0             :::111                       :::*                  
udp    UNCONN     0      0             :::812                       :::*                  
tcp    LISTEN     0      128            *:111                        *:*                  
tcp    LISTEN     0      128            *:6000                       *:*                  
tcp    LISTEN     0      5      192.168.122.1:53                         *:*                  
tcp    LISTEN     0      128            *:22                         *:*                  
tcp    LISTEN     0      128            *:4567                       *:*           
tcp    LISTEN     0      128    127.0.0.1:631                        *:*                  
tcp    LISTEN     0      128    127.0.0.1:6010                       *:*                  
tcp    LISTEN     0      80            :::3306                      :::*           
tcp    LISTEN     0      128           :::111                       :::*                  
tcp    LISTEN     0      128           :::6000                      :::*                  
tcp    LISTEN     0      128           :::22                        :::*                  
tcp    LISTEN     0      128          ::1:631                       :::*                  
tcp    LISTEN     0      128          ::1:6010                      :::*                  
  1. 找到MySQL的臨時密碼,第一次登錄要修改要不執行不了管理操作。
[[email protected] ~]#grep "password" /var/log/mysqld.log 
2019-12-03T06:13:39.187929Z 1 [Note] A temporary password is generated for [email protected]: a>#;L(Sm4Ln:

[[email protected] ~]#mysql -uroot -p'a>#;L(Sm4Ln:'   # 需要加引號引起來
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.7.27-30-57-log

Copyright (c) 2009-2019 Percona LLC and/or its affiliates
Copyright (c) 2000, 2019, 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> show databases; # 執行查看庫操作提示必須重置密碼
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement. # 在執行此語句之前,必須使用ALTER USER語句重置密碼.

mysql> alter user [email protected]'localhost' identified by 'magedu';  # 修改密碼(其他節點不用修改加入集群以後會自動同步密碼)
Query OK, 0 rows affected (0.00 sec)
mysql> exit
Bye
[[email protected] ~]#mysql -uroot -pmagedu  # 修改以後重新登錄
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 12
Server version: 5.7.27-30-57-log Percona XtraDB Cluster (GPL), Release rel30, Revision 64987d4, WSREP version 31.39, wsrep_31.39

Copyright (c) 2009-2019 Percona LLC and/or its affiliates
Copyright (c) 2000, 2019, 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>
  1. 查看變數
# 查看寫集複製相關變數
mysql> SHOW VARIABLES LIKE 'wsrep%'\G
*************************** 1. row ***************************
Variable_name: wsrep_OSU_method
        Value: TOI
*************************** 2. row ***************************
Variable_name: wsrep_RSU_commit_timeout
        Value: 5000
*************************** 3. row ***************************
Variable_name: wsrep_auto_increment_control
        Value: ON
*************************** 4. row ***************************
Variable_name: wsrep_causal_reads
        Value: OFF
*************************** 5. row ***************************
Variable_name: wsrep_certification_rules
        Value: strict
*************************** 6. row ***************************
Variable_name: wsrep_certify_nonPK
        Value: ON
*************************** 7. row ***************************
Variable_name: wsrep_cluster_address
        Value: gcomm://192.168.39.7,192.168.39.27,192.168.39.37
*************************** 8. row ***************************
Variable_name: wsrep_cluster_name
        Value: pxc-cluster
*************************** 9. row ***************************
Variable_name: wsrep_convert_LOCK_to_trx
        Value: OFF
*************************** 10. row ***************************
Variable_name: wsrep_data_home_dir
        Value: /var/lib/mysql/
*************************** 11. row ***************************
Variable_name: wsrep_dbug_option
        Value: 
*************************** 12. row ***************************
Variable_name: wsrep_debug
        Value: OFF
*************************** 13. row ***************************
Variable_name: wsrep_desync
        Value: OFF
*************************** 14. row ***************************
Variable_name: wsrep_dirty_reads
        Value: OFF
*************************** 15. row ***************************
Variable_name: wsrep_drupal_282555_workaround
        Value: OFF
*************************** 16. row ***************************
Variable_name: wsrep_forced_binlog_format
        Value: NONE
*************************** 17. row ***************************
Variable_name: wsrep_load_data_splitting
        Value: ON
*************************** 18. row ***************************
Variable_name: wsrep_log_conflicts
        Value: ON
*************************** 19. row ***************************
Variable_name: wsrep_max_ws_rows
        Value: 0
*************************** 20. row ***************************
Variable_name: wsrep_max_ws_size
        Value: 2147483647
*************************** 21. row ***************************
Variable_name: wsrep_node_address
        Value: 192.168.39.7
*************************** 22. row ***************************
Variable_name: wsrep_node_incoming_address
        Value: AUTO
*************************** 23. row ***************************
Variable_name: wsrep_node_name
        Value: pxc-cluster-node-1
*************************** 24. row ***************************
Variable_name: wsrep_notify_cmd
        Value: 
*************************** 25. row ***************************
Variable_name: wsrep_on
        Value: ON
*************************** 26. row ***************************
Variable_name: wsrep_preordered
        Value: OFF
*************************** 27. row ***************************
Variable_name: wsrep_provider
        Value: /usr/lib64/galera3/libgalera_smm.so
*************************** 28. row ***************************
Variable_name: wsrep_provider_options
        Value: base_dir = /var/lib/mysql/; base_host = 192.168.39.7; base_port = 4567; cert.log_conflicts = no; cert.optimistic_pa = yes; debug = no; evs.auto_evict = 0; evs.causal_keepalive_period = PT1S; evs.debug_log_mask = 0x1; evs.delay_margin = PT1S; evs.delayed_keep_period = PT30S; evs.inactive_check_period = PT0.5S; evs.inactive_timeout = PT15S; evs.info_log_mask = 0; evs.install_timeout = PT7.5S; evs.join_retrans_period = PT1S; evs.keepalive_period = PT1S; evs.max_install_timeouts = 3; evs.send_window = 10; evs.stats_report_period = PT1M; evs.suspect_timeout = PT5S; evs.use_aggregate = true; evs.user_send_window = 4; evs.version = 0; evs.view_forget_timeout = P1D; gcache.dir = /var/lib/mysql/; gcache.freeze_purge_at_seqno = -1; gcache.keep_pages_count = 0; gcache.keep_pages_size = 0; gcache.mem_size = 0; gcache.name = /var/lib/mysql//galera.cache; gcache.page_size = 128M; gcache.recover = no; gcache.size = 128M; gcomm.thread_prio = ; gcs.fc_debug = 0; gcs.fc_factor = 1; gcs.fc_limit = 100; gcs.fc_master_slave = no;
*************************** 29. row ***************************
Variable_name: wsrep_recover
        Value: OFF
*************************** 30. row ***************************
Variable_name: wsrep_reject_queries
        Value: NONE
*************************** 31. row ***************************
Variable_name: wsrep_replicate_myisam
        Value: OFF
*************************** 32. row ***************************
Variable_name: wsrep_restart_slave
        Value: OFF
*************************** 33. row ***************************
Variable_name: wsrep_retry_autocommit
        Value: 1
*************************** 34. row ***************************
Variable_name: wsrep_slave_FK_checks
        Value: ON
*************************** 35. row ***************************
Variable_name: wsrep_slave_UK_checks
        Value: OFF
*************************** 36. row ***************************
Variable_name: wsrep_slave_threads
        Value: 8
*************************** 37. row ***************************
Variable_name: wsrep_sst_auth
        Value: ********
*************************** 38. row ***************************
Variable_name: wsrep_sst_donor
        Value: 
*************************** 39. row ***************************
Variable_name: wsrep_sst_donor_rejects_queries
        Value: OFF
*************************** 40. row ***************************
Variable_name: wsrep_sst_method
        Value: xtrabackup-v2
*************************** 41. row ***************************
Variable_name: wsrep_sst_receive_address
        Value: AUTO
*************************** 42. row ***************************
Variable_name: wsrep_start_position
        Value: 00000000-0000-0000-0000-000000000000:-1
*************************** 43. row ***************************
Variable_name: wsrep_sync_wait
        Value: 0
43 rows in set (0.01 sec)

# 查看相關狀態變數
mysql> SHOW STATUS LIKE 'wsrep%'\G
*************************** 1. row ***************************
Variable_name: wsrep_local_state_uuid
        Value: 10c3398e-1594-11ea-9f84-c2cae1c33555
*************************** 2. row ***************************
Variable_name: wsrep_protocol_version
        Value: 9
*************************** 3. row ***************************
Variable_name: wsrep_last_applied
        Value: 1
*************************** 4. row ***************************
Variable_name: wsrep_last_committed
        Value: 1
*************************** 5. row ***************************
Variable_name: wsrep_replicated
        Value: 1
*************************** 6. row ***************************
Variable_name: wsrep_replicated_bytes
        Value: 232
*************************** 7. row ***************************
Variable_name: wsrep_repl_keys
        Value: 1
*************************** 8. row ***************************
Variable_name: wsrep_repl_keys_bytes
        Value: 32
*************************** 9. row ***************************
Variable_name: wsrep_repl_data_bytes
        Value: 133
*************************** 10. row ***************************
Variable_name: wsrep_repl_other_bytes
        Value: 0
*************************** 11. row ***************************
Variable_name: wsrep_received
        Value: 2
*************************** 12. row ***************************
Variable_name: wsrep_received_bytes
        Value: 154
*************************** 13. row ***************************
Variable_name: wsrep_local_commits
        Value: 0
*************************** 14. row ***************************
Variable_name: wsrep_local_cert_failures
        Value: 0
*************************** 15. row ***************************
Variable_name: wsrep_local_replays
        Value: 0
*************************** 16. row ***************************
Variable_name: wsrep_local_send_queue
        Value: 0
*************************** 17. row ***************************
Variable_name: wsrep_local_send_queue_max
        Value: 1
*************************** 18. row ***************************
Variable_name: wsrep_local_send_queue_min
        Value: 0
*************************** 19. row ***************************
Variable_name: wsrep_local_send_queue_avg
        Value: 0.000000
*************************** 20. row ***************************
Variable_name: wsrep_local_recv_queue
        Value: 0
*************************** 21. row ***************************
Variable_name: wsrep_local_recv_queue_max
        Value: 2
*************************** 22. row ***************************
Variable_name: wsrep_local_recv_queue_min
        Value: 0
*************************** 23. row ***************************
Variable_name: wsrep_local_recv_queue_avg
        Value: 0.500000
*************************** 24. row ***************************
Variable_name: wsrep_local_cached_downto
        Value: 1
*************************** 25. row ***************************
Variable_name: wsrep_flow_control_paused_ns
        Value: 0
*************************** 26. row ***************************
Variable_name: wsrep_flow_control_paused
        Value: 0.000000
*************************** 27. row ***************************
Variable_name: wsrep_flow_control_sent
        Value: 0
*************************** 28. row ***************************
Variable_name: wsrep_flow_control_recv
        Value: 0
*************************** 29. row ***************************
Variable_name: wsrep_flow_control_interval
        Value: [ 100, 100 ]
*************************** 30. row ***************************
Variable_name: wsrep_flow_control_interval_low
        Value: 100
*************************** 31. row ***************************
Variable_name: wsrep_flow_control_interval_high
        Value: 100
*************************** 32. row ***************************
Variable_name: wsrep_flow_control_status
        Value: OFF
*************************** 33. row ***************************
Variable_name: wsrep_cert_deps_distance
        Value: 1.000000
*************************** 34. row ***************************
Variable_name: wsrep_apply_oooe
        Value: 0.000000
*************************** 35. row ***************************
Variable_name: wsrep_apply_oool
        Value: 0.000000
*************************** 36. row ***************************
Variable_name: wsrep_apply_window
        Value: 1.000000
*************************** 37. row ***************************
Variable_name: wsrep_commit_oooe
        Value: 0.000000
*************************** 38. row ***************************
Variable_name: wsrep_commit_oool
        Value: 0.000000
*************************** 39. row ***************************
Variable_name: wsrep_commit_window
        Value: 1.000000
*************************** 40. row ***************************
Variable_name: wsrep_local_state
        Value: 4
*************************** 41. row ***************************
Variable_name: wsrep_local_state_comment
        Value: Synced
*************************** 42. row ***************************
Variable_name: wsrep_cert_index_size
        Value: 1
*************************** 43. row ***************************
Variable_name: wsrep_cert_bucket_count
        Value: 22
*************************** 44. row ***************************
Variable_name: wsrep_gcache_pool_size
        Value: 1592
*************************** 45. row ***************************
Variable_name: wsrep_causal_reads
        Value: 0
*************************** 46. row ***************************
Variable_name: wsrep_cert_interval
        Value: 0.000000
*************************** 47. row ***************************
Variable_name: wsrep_open_transactions
        Value: 0
*************************** 48. row ***************************
Variable_name: wsrep_open_connections
        Value: 0
*************************** 49. row ***************************
Variable_name: wsrep_ist_receive_status
        Value: 
*************************** 50. row ***************************
Variable_name: wsrep_ist_receive_seqno_start
        Value: 0
*************************** 51. row ***************************
Variable_name: wsrep_ist_receive_seqno_current
        Value: 0
*************************** 52. row ***************************
Variable_name: wsrep_ist_receive_seqno_end
        Value: 0
*************************** 53. row ***************************
Variable_name: wsrep_incoming_addresses
        Value: 192.168.39.7:3306
*************************** 54. row ***************************
Variable_name: wsrep_cluster_weight
        Value: 1
*************************** 55. row ***************************
Variable_name: wsrep_desync_count
        Value: 0
*************************** 56. row ***************************
Variable_name: wsrep_evs_delayed
        Value: 
*************************** 57. row ***************************
Variable_name: wsrep_evs_evict_list
        Value: 
*************************** 58. row ***************************
Variable_name: wsrep_evs_repl_latency
        Value: 0/0/0/0/0
*************************** 59. row ***************************
Variable_name: wsrep_evs_state
        Value: OPERATIONAL
*************************** 60. row ***************************
Variable_name: wsrep_gcomm_uuid
        Value: 10c2c674-1594-11ea-83fc-6e0df986585c
*************************** 61. row ***************************
Variable_name: wsrep_cluster_conf_id
        Value: 1
*************************** 62. row ***************************
Variable_name: wsrep_cluster_size
        Value: 1
*************************** 63. row ***************************
Variable_name: wsrep_cluster_state_uuid
        Value: 10c3398e-1594-11ea-9f84-c2cae1c33555
*************************** 64. row ***************************
Variable_name: wsrep_cluster_status
        Value: Primary
*************************** 65. row ***************************
Variable_name: wsrep_connected
        Value: ON
*************************** 66. row ***************************
Variable_name: wsrep_local_bf_aborts
        Value: 0
*************************** 67. row ***************************
Variable_name: wsrep_local_index
        Value: 0
*************************** 68. row ***************************
Variable_name: wsrep_provider_name
        Value: Galera
*************************** 69. row ***************************
Variable_name: wsrep_provider_vendor
        Value: Codership Oy <[email protected]>
*************************** 70. row ***************************
Variable_name: wsrep_provider_version
        Value: 3.39(rb3295e6)
*************************** 71. row ***************************
Variable_name: wsrep_ready
        Value: ON
71 rows in set (0.00 sec)

#重點內容
mysql> SHOW STATUS like 'wsrep%';
+----------------------------------+--------------------------------------+
| Variable_name                    | Value                                |
+----------------------------------+--------------------------------------+
| wsrep_local_state_uuid           | 10c3398e-1594-11ea-9f84-c2cae1c33555 |
| wsrep_protocol_version           | 9                                    |
| wsrep_last_applied               | 1                                    |
| wsrep_last_committed             | 1                                    |
| wsrep_replicated                 | 1                                    |
| wsrep_replicated_bytes           | 232                                  |
| wsrep_repl_keys                  | 1                                    |
| wsrep_repl_keys_bytes            | 32                                   |
| wsrep_repl_data_bytes            | 133                                  |
| wsrep_repl_other_bytes           | 0                                    |
| wsrep_received                   | 2                                    |
| wsrep_received_bytes             | 154                                  |
| wsrep_local_commits              | 0                                    |
| wsrep_local_cert_failures        | 0                                    |
| wsrep_local_replays              | 0                                    |
| wsrep_local_send_queue           | 0                                    |
| wsrep_local_send_queue_max       | 1                                    |
| wsrep_local_send_queue_min       | 0                                    |
| wsrep_local_send_queue_avg       | 0.000000                             |
| wsrep_local_recv_queue           | 0                                    |
| wsrep_local_recv_queue_max       | 2                                    |
| wsrep_local_recv_queue_min       | 0                                    |
| wsrep_local_recv_queue_avg       | 0.500000                             |
| wsrep_local_cached_downto        | 1                                    |
| wsrep_flow_control_paused_ns     | 0                                    |
| wsrep_flow_control_paused        | 0.000000                             |
| wsrep_flow_control_sent          | 0                                    |
| wsrep_flow_control_recv          | 0                                    |
| wsrep_flow_control_interval      | [ 100, 100 ]                         |
| wsrep_flow_control_interval_low  | 100                                  |
| wsrep_flow_control_interval_high | 100                                  |
| wsrep_flow_control_status        | OFF                                  |
| wsrep_cert_deps_distance         | 1.000000                             |
| wsrep_apply_oooe                 | 0.000000                             |
| wsrep_apply_oool                 | 0.000000                             |
| wsrep_apply_window               | 1.000000                             |
| wsrep_commit_oooe                | 0.000000                             |
| wsrep_commit_oool                | 0.000000                             |
| wsrep_commit_window              | 1.000000                             |
| wsrep_local_state                | 4                                    |
| wsrep_local_state_comment        | Synced                               |
| wsrep_cert_index_size            | 1                                    |
| wsrep_cert_bucket_count          | 22                                   |
| wsrep_gcache_pool_size           | 1592                                 |
| wsrep_causal_reads               | 0                                    |
| wsrep_cert_interval              | 0.000000                             |
| wsrep_open_transactions          | 0                                    |
| wsrep_open_connections           | 0                                    |
| wsrep_ist_receive_status         |                                      |
| wsrep_ist_receive_seqno_start    | 0                                    |
| wsrep_ist_receive_seqno_current  | 0                                    |
| wsrep_ist_receive_seqno_end      | 0                                    |
| wsrep_incoming_addresses         | 192.168.39.7:3306                    |
| wsrep_cluster_weight             | 1                                    |
| wsrep_desync_count               | 0                                    |
| wsrep_evs_delayed                |                                      |
| wsrep_evs_evict_list             |                                      |
| wsrep_evs_repl_latency           | 0/0/0/0/0                            |
| wsrep_evs_state                  | OPERATIONAL                          |
| wsrep_gcomm_uuid                 | 10c2c674-1594-11ea-83fc-6e0df986585c |
| wsrep_cluster_conf_id            | 1                                    |
| wsrep_cluster_size               | 1                                    |
| wsrep_cluster_state_uuid         | 10c3398e-1594-11ea-9f84-c2cae1c33555 |
| wsrep_cluster_status             | Primary                              |
| wsrep_connected                  | ON                                   |
| wsrep_local_bf_aborts            | 0                                    |
| wsrep_local_index                | 0                                    |
| wsrep_provider_name              | Galera                               |
| wsrep_provider_vendor            | Codership Oy <[email protected]>    |
| wsrep_provider_version           | 3.39(rb3295e6)                       |
| wsrep_ready                      | ON                                   |
+----------------------------------+--------------------------------------+
71 rows in set (0.00 sec)
說明:
wsrep_cluster_size表示,該Galera集群中只有一個節點
wsrep_local_state_comment 狀態為Synced(4),表示數據已同步完成(因為是第一個引導節點,無數據需要同步)。 如果狀態是Joiner, 意味著 SST 沒有完成. 只有所有節點狀態是Synced,才可以加新節點
wsrep_cluster_status為Primary,且已經完全連接並準備好

啟動PXC集群中其它所有節點

  1. 啟動PXC集群中其它所有節點
# 啟動前在第一個節點上創建一個授權賬戶(要不然可能別的節點沒有授權資料庫會起不來)
mysql> GRANT RELOAD, LOCK TABLES, PROCESS, REPLICATION CLIENT ON *.* TO 'sstuser'@'localhost' identified by 'centos7'; # 這裡授權的密碼必須和配置文件里設置的密碼對應,所有伺服器都要一樣。
Query OK, 0 rows affected, 1 warning (0.00 sec)

[[email protected] etc]#ss -ntl  # 啟動前埠情況
State      Recv-Q Send-Q Local Address:Port               Peer Address:Port              
LISTEN     0      128               *:111                           *:*                  
LISTEN     0      128               *:6000                          *:*                  
LISTEN     0      5      192.168.122.1:53                            *:*                  
LISTEN     0      128               *:22                            *:*                  
LISTEN     0      128       127.0.0.1:631                           *:*                  
LISTEN     0      128       127.0.0.1:6010                          *:*                  
LISTEN     0      128              :::111                          :::*                  
LISTEN     0      128              :::6000                         :::*                  
LISTEN     0      128              :::22                           :::*                  
LISTEN     0      128             ::1:631                          :::*                  
LISTEN     0      128             ::1:6010                         :::*    

[[email protected] etc]#systemctl start mysql # 啟動資料庫
[[email protected] etc]#ss -ntl   # 啟動後 3306、4567 埠都出現了
State       Recv-Q Send-Q                                                 Local Address:Port                                                                Peer Address:Port              
LISTEN      0      128                                                                *:111                                                                            *:*                  
LISTEN      0      128                                                                *:6000                                                                           *:*                  
LISTEN      0      5                                                      192.168.122.1:53                                                                             *:*                  
LISTEN      0      128                                                                *:22                                                                             *:*                  
LISTEN      0      128                                                                *:4567                                                                           *:*                  
LISTEN      0      128                                                        127.0.0.1:631                                                                            *:*                  
LISTEN      0      128                                                        127.0.0.1:6010                                                                           *:*                  
LISTEN      0      128                                                        127.0.0.1:6011                                                                           *:*                  
LISTEN      0      80                                                                :::3306                                                                          :::*                  
LISTEN      0      128                                                               :::111                                                                           :::*                  
LISTEN      0      128                                                               :::6000                                                                          :::*                  
LISTEN      0      128                                                               :::22                                                                            :::*                  
LISTEN      0      128                                                              ::1:631                                                                           :::*                  
LISTEN      0      128                                                              ::1:6010                                                                          :::*                  
LISTEN      0      128                                                              ::1:6011                                                                          :::*         
[[email protected] etc]#mysql -uroot -pmagedu  # 登錄資料庫
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.7.27-30-57-log Percona XtraDB Cluster (GPL), Release rel30, Revision 64987d4, WSREP version 31.39, wsrep_31.39

Copyright (c) 2009-2019 Percona LLC and/or its affiliates
Copyright (c) 2000, 2019, 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> 

# 另一個節點一樣啟動
[[email protected] etc]#systemctl start mysql # 啟動資料庫
[[email protected] ~]#mysql -uroot -pmagedu
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.7.27-30-57-log Percona XtraDB Cluster (GPL), Release rel30, Revision 64987d4, WSREP version 31.39, wsrep_31.39

Copyright (c) 2009-2019 Percona LLC and/or its affiliates
Copyright (c) 2000, 2019, 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> 
  1. 查看集群狀態,驗證集群是否成功
# 在任意節點,查看集群狀態
mysql> SHOW VARIABLES LIKE 'wsrep_node_name';
+-----------------+--------------------+
| Variable_name   | Value              |
+-----------------+--------------------+
| wsrep_node_name | pxc-cluster-node-1 |
+-----------------+--------------------+
1 row in set (0.00 sec)

mysql> show variables like 'wsrep_node_address';
+--------------------+--------------+
| Variable_name      | Value        |
+--------------------+--------------+
| wsrep_node_address | 192.168.39.7 |
+--------------------+--------------+
1 row in set (0.01 sec)

mysql> show variables like 'wsrep_on';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| wsrep_on      | ON    |
+---------------+-------+
1 row in set (0.00 sec)

mysql> show status like 'wsrep_cluster_size';
+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| wsrep_cluster_size | 3     |
+--------------------+-------+
1 row in set (0.00 sec)

# 在任意節點創建資料庫測試(pxc2)
mysql> SHOW VARIABLES LIKE 'wsrep_node_address';
+--------------------+---------------+
| Variable_name      | Value         |
+--------------------+---------------+
| wsrep_node_address | 192.168.39.27 |
+--------------------+---------------+
1 row in set (0.00 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)

mysql> create database db1;
Query OK, 1 row affected (0.01 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| db1                |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)

# 在pxc1上查看
mysql> SHOW VARIABLES LIKE 'wsrep_node_address';
+--------------------+--------------+
| Variable_name      | Value        |
+--------------------+--------------+
| wsrep_node_address | 192.168.39.7 |
+--------------------+--------------+
1 row in set (0.00 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| db1                |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)

# 在pxc2上查看  
mysql> SHOW VARIABLES LIKE 'wsrep_node_address';
+--------------------+---------------+
| Variable_name      | Value         |
+--------------------+---------------+
| wsrep_node_address | 192.168.39.37 |
+--------------------+---------------+
1 row in set (0.00 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| db1                |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)
# 兩個節點都可以看到同步成功
  1. 測試是否有衝突問題
    在這裡插入圖片描述
#利用Xshell軟體,同時在三個節點資料庫,在其中一個節點成功
mysql> create database db2;  # 只有一個節點會成功其他節點報錯不創建
Query OK, 1 row affected (0.00 sec)

mysql> create database db2;
ERROR 1007 (HY000): Can't create database 'db2'; database exists 

mysql> create database db2;
ERROR 1007 (HY000): Can't create database 'db2'; database exists
  1. PXC缺點(同時寫入數據性能會有影響)
# 使用一個命令迴圈創建10w條記錄
mysql> create table test (id int auto_increment primary key,name char(10));

delimiter ;
Query OK, 0 rows affected (0.01 sec)

mysql> 
mysql> delimiter $$
mysql> 
mysql> create procedure  proc_test() 
    -> begin  
    -> declare i int;
    -> set i = 1; 
    -> while i < 100000 
    -> do  insert into test(name) values (concat('wang',i)); 
    -> set i = i +1; 
    -> end while; 
    -> end$$
Query OK, 0 rows affected (0.01 sec)

mysql> 
mysql> delimiter ;
mysql> call proc_test();
Query OK, 1 row affected (3 min 39.51 sec)   # 用了39s接近40s時間才添加完成

# 使用事務方式添加記錄還是很快的
mysql> begin;
Query OK, 0 rows affected (0.00 sec)

mysql> call proc_test();
Query OK, 1 row affected (2.44 sec)

mysql> commit;
Query OK, 0 rows affected (0.25 sec)
  1. 添加記錄的話每個節點添加id變化
# 每個節點添加記錄可重覆。(是自動增長的)
mysql> insert t1(name)values('mage');
Query OK, 1 row affected (0.01 sec)

mysql> select * from t1;
+----+-------+
| id | name  |
+----+-------+
|  1 | mage  |
|  4 | magea |
|  7 | mageb |
| 10 | mage  |
+----+-------+
4 rows in set (0.00 sec)
# 2 節點添加
mysql> insert t1(name)values('mage');
Query OK, 1 row affected (0.00 sec)

mysql> insert t1(name)values('mage');
Query OK, 1 row affected (0.00 sec)

mysql> insert t1(name)values('mage');
Query OK, 1 row affected (0.00 sec)

mysql> select * from t1;
+----+-------+
| id | name  |
+----+-------+
|  1 | mage  |
|  4 | magea |
|  7 | mageb |
| 10 | mage  |
| 11 | mage  |
| 14 | mage  |
| 17 | mage  |
+----+-------+
7 rows in set (0.00 sec)

在PXC集群中加入節點

一個節點加入到Galera集群有兩種情況:新節點加入集群、暫時離組的成員再次加入集群
1)新節點加入Galera集群
新節點加入集群時,需要從當前集群中選擇一個Donor節點來同步數據,也就是所謂state_snapshot_tranfer(SST)過程。SST同步數據的方式由選項wsrep_sst_method決定,一般選擇的是xtrabackup。
必須註意,新節點加入Galera時,會刪除新節點上所有已有數據,再通過xtrabackup(假設使用的是該方式)從Donor處完整備份所有數據進行恢復。所以,如果數據量很大,新節點加入過程會很慢。而且,在一個新節點成為Synced狀態之前,不要同時加入其它新節點,否則很容易將集群壓垮。如果是這種情況,可以考慮使用wsrep_sst_method=rsync來做增量同步,既然是增量同步,最好保證新節點上已經有一部分數據基礎,否則和全量同步沒什麼區別,且這樣會對Donor節點加上全局readonly鎖。
2)舊節點加入Galera集群
如果舊節點加入Galera集群,說明這個節點在之前已經在Galera集群中呆過,有一部分數據基礎,缺少的只是它離開集群時的數據。這時加入集群時,會採用IST(incremental snapshot transfer)傳輸機制,即使用增量傳輸。
# 同樣先配置yum源
# 在安裝資料庫
[[email protected] ~]#yum install Percona-XtraDB-Cluster-57 -y
# 修改配置文件
[[email protected] ~]#grep -Ev "^#|^$" /etc/percona-xtradb-cluster.conf.d/wsrep.cnf
[mysqld]
wsrep_provider=/usr/lib64/galera3/libgalera_smm.so
wsrep_cluster_address=gcomm://192.168.39.7,192.168.39.27,192.168.39.37,192.168.39.47 # 這一行添加上新節點的ip(雖然其他節點配置文件不添加也可以,但是最好都加上,比如說伺服器依次關機到新添加的節點(新添加的節點留為最後的引導伺服器),但是下次開機別的節點會找不到新添加的伺服器,資料庫就起不來了)
binlog_format=ROW
default_storage_engine=InnoDB
wsrep_slave_threads= 8
wsrep_log_conflicts
innodb_autoinc_lock_mode=2
wsrep_node_address=192.168.39.47
wsrep_cluster_name=pxc-cluster
wsrep_node_name=pxc-cluster-node-4
pxc_strict_mode=ENFORCING
wsrep_sst_method=xtrabackup-v2
wsrep_sst_auth="sstuser:centos7"

# 查看連接數以變為4個
mysql> show status like 'wsrep_cluster_size'\G
*************************** 1. row ***************************
Variable_name: wsrep_cluster_size
        Value: 4
1 row in set (0.00 sec)

在PXC集群中修複故障節點

  1. 在其他節點停止服務
[[email protected] ~]#systemctl stop mysql
[[email protected] ~]#systemctl status mysql
● mysql.service - Percona XtraDB Cluster
   Loaded: loaded (/usr/lib/systemd/system/mysql.service; enabled; vendor preset: disabled)
   Active: inactive (dead) since Tue 2019-12-03 16:52:51 CST; 3min 21s ago
  Process: 29259 ExecStopPost=/usr/bin/mysql-systemd stop-post (code=exited, status=0/SUCCESS)
  Process: 29221 ExecStop=/usr/bin/mysql-systemd stop (code=exited, status=0/SUCCESS)
  Process: 26928 ExecStartPost=/usr/bin/mysql-systemd start-post $MAINPID (code=exited, status=0/SUCCESS)
  Process: 26925 ExecStart=/usr/bin/mysqld_safe --basedir=/usr (code=exited, status=0/SUCCESS)
  Process: 26853 ExecStartPre=/usr/bin/mysql-systemd start-pre (code=exited, status=0/SUCCESS)
 Main PID: 26925 (code=exited, status=0/SUCCESS)

Dec 03 15:12:54 pxc2 mysqld_safe[26925]: 2019-12-03T07:12:54.344288Z mysqld_safe Assigning 00000000-0000-0000-0000-000000000000:-1 to wsrep_start_position
Dec 03 15:12:56 pxc2 mysql-systemd[26928]: State transfer in progress, setting sleep higher
Dec 03 15:13:16 pxc2 mysql-systemd[26928]: SUCCESS!
Dec 03 15:13:16 pxc2 systemd[1]: Started Percona XtraDB Cluster.
Dec 03 16:52:39 centos7.localdomain systemd[1]: Stopping Percona XtraDB Cluster...
Dec 03 16:52:39 centos7.localdomain mysql-systemd[29221]: SUCCESS! Stopping Percona XtraDB Cluster......
Dec 03 16:52:51 centos7.localdomain mysqld_safe[26925]: 2019-12-03T08:52:51.720383Z mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended
Dec 03 16:52:51 centos7.localdomain mysql-systemd[29259]: WARNING: mysql pid file /var/run/mysqld/mysqld.pid empty or not readable
Dec 03 16:52:51 centos7.localdomain mysql-systemd[29259]: WARNING: mysql may be already dead
Dec 03 16:52:51 centos7.localdomain systemd[1]: Stopped Percona XtraDB Cluster.
  1. 在其它任意節點查看wsrep_cluster_size變數
[[email protected] ~]#mysql -uroot -pmagedu
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 21
Server version: 5.7.27-30-57-log Percona XtraDB Cluster (GPL), Release rel30, Revision 64987d4, WSREP version 31.39, wsrep_31.39

Copyright (c) 2009-2019 Percona LLC and/or its affiliates
Copyright (c) 2000, 2019, 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> show status like 'wsrep_cluster_size'\G
*************************** 1. row ***************************
Variable_name: wsrep_cluster_size
        Value: 3                          # 少了一個節點
1 row in set (0.00 sec)
  1. 添加一個資料庫查看同步情況
mysql> create database db4;
Query OK, 1 row affected (0.01 sec)

#在其它任意節點可看到數據已同步
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| db1                |
| db2                |
| db3                |
| db4                |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
8 rows in set (0.00 sec)
# 其他節點正常同步
  1. 恢復服務,數據同步
[[email protected] ~]#systemctl start mysql
[[email protected] ~]#mysql -uroot -pmagedu
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.7.27-30-57-log Percona XtraDB Cluster (GPL), Release rel30, Revision 64987d4, WSREP version 31.39, wsrep_31.39

Copyright (c) 2009-2019 Percona LLC and/or its affiliates
Copyright (c) 2000, 2019, 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> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| db1                |
| db2                |
| db3                |
| db4                |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
8 rows in set (0.00 sec)
# 恢復服務之後數據還是能同步的
mysql> SHOW STATUS LIKE 'wsrep_cluster_size';
+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| wsrep_cluster_size | 4     |
+--------------------+-------+
1 row in set (0.00 sec)

實現MariaDB Galera Cluster

#在三個節點上都實現
[[email protected] ~]

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