一、說明

前面我們說了mysql的安裝配置,mysql語句使用以及備份恢復mysql資料;本次要介紹的是mysql的主從複製,讀寫分離;及高可用MHA;

環境如下:

master:CentOS7_x64 mysql5.721 172.16.3.175 db1
slave1:CentOS7_x64 mysql5.7.21 172.16.3.235 db2
slave2:CentOS7_x64 mysql5.7.21 172.16.3.235 db3
proxysql/MHA:CentOS7_x64 mysql5.7.21 172.16.3.235 proxysql

架構圖:

說明:

配置測試時為了方便關閉了防火牆頭,selinux安全策略;

二、主從複製配置

一臺主資料庫,N從節點;從節點開啟兩個執行緒,通過Slave_IO_Running執行緒和主節點上有許可權的賬號從 主資料庫節點複製binlog日誌到本地,能過Slave_SQL_Running執行緒在本地執行binlog日誌,達到主從節點內容同步;

master配置:

egrep -v '(^$|^#)' /usr/local/mysql/etc/my.cnf

[mysqld]
datadir=/data1/mysqldb
socket=/tmp/mysql.sock
key_buffer_size   = 16M
max_allowed_packet  = 16M
thread_stack   = 192K
thread_cache_size  = 8
query_cache_limit  = 1M
query_cache_size  = 64M
query_cache_type  = 1
symbolic-links=0
innodb_file_per_table=ON
skip_name_resolve=ON

server-id  = 1
log_bin   = /data1/mysqldb/mysql-bin.log
[mysqld_safe]
log-error=/usr/local/mysql/logs/error.log
pid-file=/data1/mysqldb/mysql.pid
!includedir /usr/local/mysql/etc/my.cnf.d

建立從節點同步賬號:

mysql > grant replication client,replication slave on *.* to 'repluser'@'172.16.3.%' identified by 'replpass';
mysql > flush privileges;
mysql >show master logs;
+------------------+-----------+
| Log_name   | File_size |
+------------------+-----------+
| mysql-bin.000001 |  622 |

主節點上的binlog日誌檔案及位置;請記下;從節點第一次同步時需要用;

slave節點:

egrep -v '(^$|^#)' /usr/local/mysql/etc/my.cnf

[mysqld]
datadir=/data1/mysqldb
socket=/data1/mysqldb/mysql.sock
key_buffer_size   = 16M
max_allowed_packet  = 16M
thread_stack   = 192K
thread_cache_size  = 8
query_cache_limit  = 1M
query_cache_size  = 64M
query_cache_type  = 1
symbolic-links=0

innodb_file_per_table=ON
skip_name_resolve=ON

server-id    = 11   #從節點標識ID 各從節點均不一樣 
relay_log = relay-log
read_only=ON

[mysqld_safe]
log-error=/usr/local/mysql/log/error.log
pid-file=/var/run/mysql/mysql.pid
!includedir /usr/local/mysql/etc/my.cnf.d

啟動mysq資料庫

注意:兩臺從節點的server-id 值不一樣;其他的都一樣;因此從節點只展示一個配置檔案;
登入資料庫並同步資料啟動slave

兩臺slave均要同步並啟動

mysql > CHANGE MASTER TO MASTER_HOST="172.16.3.175",MASTER_USER="repluser",MASTER_PASSWORD="replpass",MASTER_PORT=3306,MASTER_LOG_FILE="mysql-bin.000001",MASTER_LOG_POS=622;
mysql > start slave;  #啟動從節點()

#檢視從節點狀態
mysql > SHOW SLAVE STATUS;
*************************** 1. row ***************************
    Slave_IO_State: Waiting for master to send event
     Master_Host: 172.16.3.175     #主節點
     Master_User: repluser       #同步賬號
     Master_Port: 3306
    Connect_Retry: 60
    Master_Log_File: mysql-bin.000001
   Read_Master_Log_Pos: 622
    Relay_Log_File: relay-log.000001
    Relay_Log_Pos: 582
  Relay_Master_Log_File: mysql-bin.000001
    Slave_IO_Running: Yes      #同步執行緒正常
   Slave_SQL_Running: Yes     #本地寫執行緒正常
    Replicate_Do_DB:        #同步過濾為空(可以只同步某個或某些庫)
   Replicate_Ignore_DB:        #不同步的庫
   Replicate_Do_Table:      
  Replicate_Ignore_Table: 
  Replicate_Wild_Do_Table: 
 Replicate_Wild_Ignore_Table: 
     Last_Errno: 0    #最後同步的錯誤 0表示正常同步
     Last_Error: 
     Skip_Counter: 0
   Exec_Master_Log_Pos: 622
    Relay_Log_Space: 615
    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: 57017c43-36e3-11e8-ac76-080027393fc7
    Master_Info_File: /data1/mysqldb/master.info
     SQL_Delay: 0
   SQL_Remaining_Delay: NULL
  Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
   Master_Retry_Count: 86400
     Master_Bind: 
  Last_IO_Error_Timestamp: 
  Last_SQL_Error_Timestamp: 
    Master_SSL_Crl: 
   Master_SSL_Crlpath: 
   Retrieved_Gtid_Set: 
   Executed_Gtid_Set: 
    Auto_Position: 0
   Replicate_Rewrite_DB: 
     Channel_Name: 
   Master_TLS_Version: 
1 row in set (0.00 sec)
ERROR: 
No query specified

測試主從同步

在master匯入測試資料;修改資料並檢視slave 中的資料是否一致;

[root@db1 ~]# mysql < Testdb.sql
登入資料庫
[root@db1 ~]# mysql -uroot -p
mysql> show databases;
+--------------------+
| Database   |
+--------------------+
 study    |
+--------------------+
5 rows in set (0.00 sec)
###study測試資料庫匯入成功
mysql> use study;
Database changed
mysql> show tables;
+-----------------+
| Tables_in_study |
+-----------------+
| class   |
| course   |
| part   |
| score   |
| student   |
| tb31   |
| tb32   |
| teacher   |
| test1   |
| test2   |
| user_info  |
+-----------------+
11 rows in set (0.00 sec)
#刪除test1 test2表

slave從節點上檢視

mysql> show tables;
+-----------------+
| Tables_in_study |
+-----------------+
| class   |
| course   |
| part   |
| score   |
| student   |
| tb31   |
| tb32   |
| teacher   |
| user_info  |
+-----------------+
9 rows in set (0.00 sec)

資料已經可以正常同步;注意主從同步只需要第一次手動啟動;之後都隨mysql服務自動啟動;主從同步架構只方便了資料的同步,此時如果沒有 第三方工具介入想做到讀寫分離就需要在程式中去做,難免出錯;而出錯了,就需要手動同步資料；這裡通過proxysql來做讀寫分離;

三、proxysql之讀寫分離

以上已經完成了主從複製配置;然而這只是一個基本配置,加上一個proxysql實現mysql讀寫分離,proxysql類似haproxy七層代理路由功能且支援MySQL 協議的的資料庫代理；是dba開發給dba使用的;使用者請求發向proxysql,如果是寫請求發往主節點;讀請求發下從節點組中;以此實現讀寫分離;一定程式上減輕了主資料庫的io壓力;
下載安裝proxysql
目前最新版本是1.4.7-1(由於最新版本有問題)
我們這裡下載使用1.3.6-1的基於CentOS7的rpm包;下載到本地並yum安裝

[root@proxysql ~]# yum install proxysql-1.3.6-1-centos7.x86_64.rpm -y
[root@proxysql ~]# rpm -ql proxysql
/etc/init.d/proxysql
/etc/proxysql.cnf  #主配置檔案
/usr/bin/proxysql
/usr/share/proxysql/tools/proxysql_galera_checker.sh
/usr/share/proxysql/tools/proxysql_galera_writer.pl

配置如下:

在配置proxysql之前需要在主節點配置授權賬號以作proxysql對主從節點操作;另外proxysql上的mysql客戶端工具需要和主從節點上的保持一致;
在主節點master上授權登入賬號：

mysql > GRANT ALL ON *.* TO 'myadmin'@'172.16.3.%' identified by 'mypass';

proxysql.cnf配置

[root@proxysql ~]# egrep -v '(^$|^#)' /etc/proxysql.cnf

datadir="/var/lib/proxysql"
admin_variables=
{ 
 admin_credentials="admin:admin"    #proxysql自己的管理使用者名稱密碼
 mysql_ifaces="127.0.0.1:6032;/tmp/proxysql_admin.sock"
}
mysql_variables=
{
 threads=4       #執行緒數,建議和cpu核心數一致
 max_connections=2048  #最大連線
 default_query_delay=0
 default_query_timeout=36000000
 have_compress=true
 poll_timeout=2000
 interfaces="0.0.0.0:3306;/tmp/proxysql.sock"    #對外介面
 default_schema="information_schema"
 stacksize=1048576
 server_version="5.5.30"
 connect_timeout_server=3000
 monitor_username="monitor"
 monitor_password="monitor"
 monitor_history=600000
 monitor_connect_interval=60000
 monitor_ping_interval=10000
 monitor_read_only_interval=1500
 monitor_read_only_timeout=500
 ping_interval_server_msec=120000
 ping_timeout_server=500
 commands_stats=true
 sessions_sort=true
 connect_retries_on_failure=10
}

#####主從節點的配置
mysql_servers =      
(
 {
  address = "172.16.3.175" # no default,required . If port is 0,address is interpred as a Unix Socket Domain
  port = 3306   # no default,address is interpred as a Unix Socket Domain
  hostgroup = 1   # 設定組號
  status = "ONLINE"  # default: ONLINE
  weight = 1   # default: 1
  compression = 0  # default: 0
  max_connections = 200   ###定義最大的連線
 },{
  address = "172.16.3.235" # no default,address is interpred as a Unix Socket Domain
  hostgroup = 2   # no default,required
  status = "ONLINE"  # default: ONLINE
  weight = 1   # default: 1
  compression = 0  # default: 0
  max_connections=1000
 },{
  address = "172.16.3.241" # no default,required
  status = "ONLINE"  # default: ONLINE
  weight = 1   # default: 1
  compression = 0  # default: 0
  max_connections=1000
 }
)
mysql_users:
(
 {
  username = "myadmin" # no default,required
  password = "mypass" # default: ''
  default_hostgroup = 1 # default: 0
  max_connections=1000
  default_schema="test"
  active = 1   #是否啟用
 }
)
mysql_query_rules:
(
)
scheduler=
(
)
mysql_replication_hostgroups=
(
  {
    writer_hostgroup=1   #定義寫組號1
    reader_hostgroup=2  #定義讀組號2
    comment="test repl 1" #註釋內容
  }
)

啟動proxysql服務

[root@proxysql ~]# service proxysql start

測試proxysql

模擬通過proxysql使用資料庫
[root@proxysql ]# mysql -h172.16.3.175 -umyadmin -pmypass
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 17406
Server version: 5.7.21-log MySQL Community Server (GPL)
Copyright (c) 2000,2018,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> 

mysql > show databases;
mysql> show databases;
+--------------------+
| Database   |
+--------------------+
| information_schema |
| mysql    |
| performance_schema |
| study    |
| sys    |
+--------------------+
5 rows in set (0.00 sec)
###刪除study資料庫user_info中6 -12之間的資料
刪除之前:
mysql> select * from user_info;
+-----+-------+------+--------+----------+
| nid | name | age | gender | part_nid |
+-----+-------+------+--------+----------+
| 1 | san | 20 | 男  |  1 |
| 2 | dong | 29 | 男  |  2 |
| 4 | Ling | 28 | 男  |  4 |
| 5 | ling | 28 | 男  |  3 |
| 6 | dong | 30 | 男  |  1 |
| 7 | b  | 11 | 女  |  1 |
| 8 | c  | 12 | 女  |  1 |
| 9 | d  | 18 | 女  |  4 |
| 10 | e  | 22 | 男  |  3 |
| 11 | f  | 23 | 男  |  2 |
| 12 | dongy | 22 | 男  |  1 |
+-----+-------+------+--------+----------+
11 rows in set (0.00 sec)
刪除之後:
mysql> delete from user_info where nid >6 and nid <12;
Query OK,5 rows affected (0.03 sec)

mysql> select * from user_info;
+-----+-------+------+--------+----------+
| nid | name | age | gender | part_nid |
+-----+-------+------+--------+----------+
| 1 | san | 20 | 男  |  1 |
| 2 | dong | 29 | 男  |  2 |
| 4 | Ling | 28 | 男  |  4 |
| 5 | ling | 28 | 男  |  3 |
| 6 | dong | 30 | 男  |  1 |
| 12 | dongy | 22 | 男  |  1 |
+-----+-------+------+--------+----------+
6 rows in set (0.00 sec)

到主從節點上檢視,會發現以上的查和修改資料都被proxysql正確的代理到後端處理了;
以上看了並不直觀;為了檢視proxysql與各主從節點通訊我們在主從節點上安裝tcpdump並過濾包

主節點:
類似如下:
[root@db1 ~]# tcpdump -i enp0s3 -nn tcp port 3306
tcpdump: verbose output suppressed,use -v or -vv for full protocol decode
listening on enp0s3,link-type EN10MB (Ethernet),capture size 262144 bytes
18:04:34.678861 IP 172.16.3.254.42191 > 172.16.3.175.3306: Flags [S],seq 3385407732,win 29200,options [mss 1460,sackOK,TS val 17576713 ecr 0,nop,wscale 7],length 0
18:04:34.678908 IP 172.16.3.175.3306 > 172.16.3.254.42191: Flags [S.],seq 1579426335,ack 3385407733,win 28960,TS val 29413673 ecr 17576713,length 0
18:04:34.680902 IP 172.16.3.254.42191 > 172.16.3.175.3306: Flags [.],ack 1,win 229,options [nop,TS val 17576715 ecr 29413673],length 0
18:04:34.681264 IP 172.16.3.175.3306 > 172.16.3.254.42191: Flags [P.],seq 1:83,win 227,TS val 29413675 ecr 17576715],length 82
....
從節點:
類似如下:
[root@db2 data1]# tcpdump -i enp0s3 -nn tcp port 3306
tcpdump: verbose output suppressed,capture size 262144 bytes
18:02:57.932043 IP 172.16.3.254.42733 > 172.16.3.235.3306: Flags [S],seq 76520456,TS val 17479189 ecr 0,length 0
...........

proxysql命令列管理介面:支援執行時修改

 [root@proxysql]# mysql -u admin -padmin -h 127.0.0.1 -P6032 --prompt='Admin> '
Admin> show databases;
+-----+---------+-------------------------------+
| seq | name | file       |
+-----+---------+-------------------------------+
| 0 | main |        |
| 2 | disk | /var/lib/proxysql/proxysql.db |
| 3 | stats |        |
| 4 | monitor |        |
+-----+---------+-------------------------------+
4 rows in set (0.00 sec)

以上stats,monitor,main都從配置檔案中獲取的資料庫;可以通過類似mysql執行時修改;而不需要重啟;

至此我們基於proxysql主從複製讀寫分離架構已經完成;
雙主或多主模型是無須實現讀寫分離，僅需要負載均衡：haproxy,nginx,lvs等;
proxysql並沒有解決,當主資料巖機時的問題;此時就需要量MHA來解決 ;後續再介紹;