MySQL高可用之——keepalivd+互為主從
目標：配置一個keepalived雙機熱備架構，並配置主從復制
規劃：
master1 zlm177 192.168.17.177
master2 zlm188 192.168.17.188
vip 192.168.17.166
環境： Red Hat Enterprise Linux 6.4
Percona Server 5.6.15
一、軟件安裝
可以去官網http://www.keepalived.org/software/下載最新版本的keepalived，目前最新的是1.2.13版，如下：
keepalived-1.2.13.tar
cp keepalived-1.2.13.tar /usr/local/src
cd /usr/local/src
tar zxvf keepalived-1.2.13.tar -C /opt/
cd /opt/keepalived-1.2.13
./configure --prefix=/usr/local/keepalived
make;makeinstall 或 make && makeinstall
注意，在編譯過程中會提示缺少gcc和openssl包，用yum install裝一下就可以了
RHEL6.4也可以配置CentOS的yum，具體方法這裡就不講了
yum install gcc
yum install openssl openssl-devel
還會提示xxx依賴包也需要安裝，一並裝上，用yum的好處就是安裝方便，讓系統自動判斷需要哪些包，自動下載並安裝，完成編譯以後，軟件安裝就結束了
二、配置軟件參數（VRRP）
裝完軟件後，默認會配置文件的路徑為：
/usr/local/keepalived/etc/keepalived/keepalived.conf
在主端打開該配置文件，把原有內容清空，再添加以下內容：
! Configuration File for keepalived
global_defs { --全局配置
notification_email {
[email protected] --接收通知的郵箱
}
router_id aaron8219 --可以用字母，也可以使數字，可以一致，也可以不一致，只是一個標識
}
vrrp_instance my_177 {
state BACKUP --BACKUP從端模式
interface eth0
virtual_router_id 88 --默認為51，取值范圍在1~255的整數，主從兩端必須一致，才表示是同一個組
priority 90
advert_int 1 --檢查間隔，默認1s
nopreempt --設置非搶占模式,
authentication {
auth_type PASS
auth_pass 1234
}
virtual_ipaddress { --指定vip,
192.168.17.166
}
}
##關於vip的說明：vip隨著state的變化而增加刪除，當state為master的時候就添加，當state為backup的時候刪除，主要是由優先級來決定的，和state設置的值沒有多大關系(state相同的情況下)，至於vip到底在主端還是從端，還和nopreempt有關，這裡vip可以設置多個IP地址
##關於nopreempt的說明：只能設置在state為backup的節點上，且這個節點的優先級必須比另外的高
virtual_server 192.168.17.166 3306 { --虛擬服務器ip和端口
delay_loop 2
lb_algo wrr --帶有權重的輪詢
lb_kind DR
persistence_timeout 60
protocol TCP
real_server 192.168.17.177 3306 { --真實服務器ip和端口
weight 3 --權重為3
notify_down /opt/mysql/mysql.sh --指定自殺腳本的路徑
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 3306
}
}
}
從端的配置文件大同小異，只要把IP和實例名改成自己的就可以了，並且設置從端的priority為90，而主端為100
有一點要注意的是，主從兩端的state，都配置成了backup，因為使用了nopreempt，即非搶占模式
舉個例子，當主端先啟動mysql實例和keepalived後，如果此時從端也啟動了mysql實例和keepalived，那麼vip不會跳到從端上去，即使它的優先級為100，要大於主端的90
而如果不設置nopreempt，那麼這個時候，又分2種情況：
1.state相同，即都是master或都是backup
優先級高的，會占有vip，和角色無關
2.state不同，即master->backup或backup->master
優先級高的，會占有vip，和角色無關
前提不同，結果都是一樣的，即優先級是主導，誰的優先級高，vip就漂到誰那裡
創建一個自殺腳本來判斷mysql進程是否啟動
touch /opt/mysql/mysql.sh
添加以下內容：
#!/bin.sh
pkill keepalived --表示kill掉keepalived進程
三、運行測試
/usr/local/keepalived/sbin/keepalived -f /usr/local/keepalived/etc/keepalived/keepalived.conf -D
-f 指定keepalived的參數文件
-D 表示在操作系統日志裡顯示詳細記錄
判斷keepalived進程是否正常啟動，只要查看/var/log/messages裡的日志就可以了
tail -30f /var/log/message
注意，如果沒有啟動mysql而先啟動了keepalived，那麼之前notify_down參數中指定的腳本就會被執行，表示沒有找到mysql進程，把keeplied自己的進程給kill掉。
Jul 25 02:51:22 zlm188 Keepalived[3440]: Starting Keepalived v1.2.13 (07/22,2014)
Jul 25 02:51:22 zlm188 Keepalived[3441]: Starting Healthcheck child process, pid=3442
Jul 25 02:51:22 zlm188 Keepalived[3441]: Starting VRRP child process, pid=3443
Jul 25 02:51:22 zlm188 Keepalived_vrrp[3443]: Netlink reflector reports IP 192.168.17.188 added
Jul 25 02:51:22 zlm188 Keepalived_healthcheckers[3442]: Netlink reflector reports IP 192.168.17.188 added
Jul 25 02:51:22 zlm188 Keepalived_healthcheckers[3442]: Netlink reflector reports IP fe80::a00:27ff:fe71:6b7b added
Jul 25 02:51:22 zlm188 Keepalived_healthcheckers[3442]: Registering Kernel netlink reflector
Jul 25 02:51:22 zlm188 Keepalived_vrrp[3443]: Netlink reflector reports IP fe80::a00:27ff:fe71:6b7b added
Jul 25 02:51:22 zlm188 Keepalived_healthcheckers[3442]: Registering Kernel netlink command channel
Jul 25 02:51:22 zlm188 Keepalived_vrrp[3443]: Registering Kernel netlink reflector
Jul 25 02:51:22 zlm188 Keepalived_vrrp[3443]: Registering Kernel netlink command channel
Jul 25 02:51:22 zlm188 Keepalived_vrrp[3443]: Registering gratuitous ARP shared channel
Jul 25 02:51:22 zlm188 Keepalived_vrrp[3443]: Opening file '/usr/local/keepalived/etc/keepalived/keepalived.conf'.
Jul 25 02:51:22 zlm188 Keepalived_healthcheckers[3442]: Opening file '/usr/local/keepalived/etc/keepalived/keepalived.conf'.
Jul 25 02:51:22 zlm188 Keepalived_healthcheckers[3442]: Configuration is using : 11566 Bytes
Jul 25 02:51:22 zlm188 Keepalived_vrrp[3443]: Configuration is using : 62964 Bytes
Jul 25 02:51:22 zlm188 Keepalived_vrrp[3443]: Using LinkWatch kernel netlink reflector...
Jul 25 02:51:22 zlm188 Keepalived_vrrp[3443]: VRRP_Instance(my_178) Entering BACKUP STATE
Jul 25 02:51:22 zlm188 Keepalived_vrrp[3443]: VRRP sockpool: [ifindex(2), proto(112), unicast(0), fd(10,11)]
Jul 25 02:51:22 zlm188 Keepalived_healthcheckers[3442]: Using LinkWatch kernel netlink reflector...
Jul 25 02:51:22 zlm188 Keepalived_healthcheckers[3442]: Activating healthchecker for service [192.168.17.188]:3306
Jul 25 02:51:25 zlm188 Keepalived_healthcheckers[3442]: TCP connection to [192.168.17.188]:3306 failed !!!
Jul 25 02:51:25 zlm188 Keepalived_healthcheckers[3442]: Removing service [192.168.17.188]:3306 from VS [192.168.17.166]:3306
Jul 25 02:51:25 zlm188 Keepalived_healthcheckers[3442]: Executing [/opt/mysql/mysql.sh] for service [192.168.17.188]:3306 in VS [192.168.17.166]:3306
Jul 25 02:51:25 zlm188 Keepalived_healthcheckers[3442]: Lost quorum 1-0=1 > 0 for VS [192.168.17.166]:3306
Jul 25 02:51:25 zlm188 Keepalived[3441]: Stopping Keepalived v1.2.13 (07/22,2014)
在從端啟動keepalived，跟蹤日志文件可以發現，跑了一遍以後自動stopping了，這也說明，之前的配置是ok的了，否則就要檢查一下，哪裡配置有誤，尤其要注意virtual_route_id必須保持一致，而route_id則不強行要求一致，實例名也不要重復
1.檢驗vip的情況
#ip address show或ip a show
2.用vip登錄mysql數據庫(前提是已開啟了mysqld和keepalived進程)
#mysql -h192.168.17.166 -uaaron8219 -pzlm
3.關閉某一端網卡後，測試vip的去向，以及是否能通過vip正常登陸
#ifdown eth0
#ip a show
#mysql -h192.168.17.166 -uaaron8219 -pzlm
4.重啟某一端(主機模擬主機故障)，測試vip的去向，以及是否能通過vip正常登陸
#init 6
#ip a show
#mysql -h192.168.17.166 -uaaron8219 -pzlm
5.直接kill掉keepalived進程，測試vip的去向，以及是否能通過vip正常登陸
#pkill keepalived
#ip a show
#mysql -h192.168.17.166 -uaaron8219 -pzlm
四、配置數據庫同步
安裝完keepalived，只是保證了mysql數據庫的高可用性，但是要真正做到互為主從，還需要配置MySQL主從復制模式，使數據庫可以達到一致性狀態
1.兩端配置同步所需參數
確保server-id與slave不一致，通常server-id的格式可以設置成ip末尾2-3位+端口號
比如我的環境master的ip是192.168.17.177，端口是3306
那麼server-id可以設置成1773306，相應地，slave就設置成1883306
以下參數都是在/etc/my.cnf文件中配置
server-id=1773306
log-bin=percona-bin --啟用binlog
set-variable=binlog-ignore-db=mysql --不記錄數據庫mysql的更新日志，避免了Master上的權限設置等被同步到Slave上
2.兩端添加復制用戶
mysql> grant repliecation slave on *.* to 'rep'@'192.168.17.%' identified by 'rep';
如果想要在Slave上有權限執行 "LOAD TABLE FROM MASTER" 或 "LOAD DATA FROM MASTER" 語句的話，必須授予全局的 FILE 和 Select 權限：
mysql> GRANT FILE,Select,REPLICATION SLAVE ON *.* TO 'rep'@'%' IDENTIFIED BY 'rep';
3.設置同步
如果是新庫，兩邊直接重置master的binlog
mysql> reset master;
(否則，需要把master的庫用mysqldump導出（或直接打包壓縮），再復制到從庫主機，大致步驟如下：
①mysql> flush tables with read lock;
②mysql> mysqldump -uroot -p --all-databases -l -F >full_db.sql
scp full_db.sql [email protected]:/data/mysql/percona_3306/data
或
②cd /data/mysql/percona_3306
tar zcvf data.tar.gz ./data
scp data.tar.gz [email protected]
③mysql> unlock tables;
從庫導入主庫的數據庫
mysql> mysql -uroot -p </data/mysql/percona_3306/data/full_db.sql
或
mysql> source /data/mysql/percona_3306/data/full_db.sql
)
4.主庫查詢日志狀態
mysql> show master status\G
5.從庫根據主庫的binlog位置和position來執行同步
mysql> change master to master_host='192.168.17.177',master_user='rep',master_password='rep',
master_log_file='percona-bin.000001',master_log_pos='120';
6.啟動slave
mysql> start slave;
啟動後報錯
Slave I/O: Fatal error: The slave I/O thread stops because master and slave have equal MySQL server UUIDs; these UUIDs must be different for replication to work. Error_code: 1593
因為從庫是直接通過虛擬機拷貝鏡像的方式創建的，所以UUID重復了，UUID是存放在
/data/mysql/percona_3306/data/auto.cnf文件中的
可以把這個文件直接刪除，或者編輯該文件，修改裡面的UUID和主庫不同即可，正常以後，應該是以下的狀態：
(testing)root@localhost [(none)]> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.17.177
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: percona-bin.000011
Read_Master_Log_Pos: 540
Relay_Log_File: node78-relay-bin.000018
Relay_Log_Pos: 285
Relay_Master_Log_File: percona-bin.000011
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: 540
Relay_Log_Space: 459
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: 773306
Master_UUID: 917ecbfc-10dc-11e4-b624-080027267b03
Master_Info_File: /data/mysql/percona_3306/data/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:
Executed_Gtid_Set:
Auto_Position: 0
7.測試
主庫測試數據庫zlm的tb_zlm表中執行插入一行數據：
(testing)root@localhost [(none)]> select * from zlm.tb_zlm;
+------+-----------+
| id | name |
+------+-----------+
| 1 | aaron8219 |
| 2 | zlm |
| 3 | abc |
+------+-----------+
3 rows in set (0.00 sec)
(testing)root@localhost [(none)]> insert into zlm.tb_zlm values(4,'def');
Query OK, 1 row affected (0.03 sec)
從庫查詢zlm.tb_zlm表：
(testing)root@localhost [(none)]> select * from zlm.tb_zlm;
+------+-----------+
| id | name |
+------+-----------+
| 1 | aaron8219 |
| 2 | zlm |
| 3 | abc |
| 4 | def |
+------+-----------+
4 rows in set (0.00 sec)
從庫上也進行同樣的配置，即可完成互為主從，只要從相應的master的binlog的pos位置開始change maseter就可以了
結論：只要配置的VRRP組裡面有一台機器開啟了mysqld和keepalived進程，任何通過vip實現的數據庫連接訪問，都是正常的，這樣無論是哪個節點down掉了，都不會影響mysql數據庫的可用性，是一個最簡單的mysql高可用架構。自此，通過keepalived來實現互為主從的雙機熱備架構就完成了，如果再復雜一點，安裝lvpsadm來實現虛擬服務器的配置，那麼就是一個經典的keepalived+lvs架構
