一、简述HA高可用集群
高可用集群就是当集群中的一个节点发生各种软硬件及人为故障时，集群中的其他节点能够自动接管故障节点的资源并向外提供服务。以实现减少业务中断时间，为用户提供更可靠，更高效的服务。
二、基于nfs实现mysql的高可用集群配置
环境准备接上文
实验环境：
nfs server准备
、在nfs server准备LVM存储空间
[root@node3 ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x61284c6a.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable. Warning: invalid flag 0x0000 of partition table will be corrected by w(rite) WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u'). Command (m for help): n
Command action
e extended
p primary partition (-)
p
Partition number (-):
First cylinder (-, default ):
Using default value
Last cylinder, +cylinders or +size{K,M,G} (-, default ): +10G
Value out of range.
Last cylinder, +cylinders or +size{K,M,G} (-, default ): +5G Command (m for help): t
Selected partition
Hex code (type L to list codes): 8e
Changed system type of partition to 8e (Linux LVM) Command (m for help): w
The partition table has been altered! Calling ioctl() to re-read partition table.
Syncing disks. [root@node3 ~]# partx -a /dev/sdb [root@node3 ~]# pvcreate /dev/sdb3
Physical volume "/dev/sdb3" successfully created
[root@node3 ~]# vgcreate myvg /dev/sdb3
Volume group "myvg" successfully created
[root@node3 ~]# lvcreate -L 5G -n mydata myvg
Logical volume "mydata" created.
[root@node3 ~]# mke2fs -t ext4 /dev/myvg/mydata
mke2fs 1.41. (-May-)
Filesystem label=
OS type: Linux
Block size= (log=)
Fragment size= (log=)
Stride= blocks, Stripe width= blocks
inodes, blocks
blocks (5.00%) reserved for the super user
First data block=
Maximum filesystem blocks=
block groups
blocks per group, fragments per group
inodes per group
Superblock backups stored on blocks:
, , , , , , Writing inode tables: done
Creating journal ( blocks): done
Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every mounts or
days, whichever comes first. Use tune2fs -c or -i to override. 、开机自动挂载，并nfs导出
[root@node3 ~]# mkdir /mydata
[root@node3 ~]# vim /etc/fstab
/dev/myvg/mydata /mydata ext4 defaults
[root@node3 ~]# mount -a
[root@node3 ~]# mount | grep /mydata
/dev/mapper/myvg-mydata on /mydata type ext4 (rw) [root@node3 ~]# vim /etc/exports
/mydata 192.168.0.0/(rw,no_root_squash)
#共享给192.168.0./24网段，可读可写，允许root用户登录便于初始化，配置结束可取消root用户登录 、导出nfs共享目录
#创建mysql用户，指明uid，gid。各节点的mysql用户uid，gid一致。
[root@node3 ~]# groupadd -r -g mysql
[root@node3 ~]# useradd -r -g -u mysql #创建共享目录，并修改属主属组。
[root@node3 ~]# mkdir /mydata/data
[root@node3 ~]# chown -R mysql.mysql /mydata/data #导出nfs共享目录
[root@node3 ~]# exportfs -arv
exporting 192.168.0.0/:/mydata
各节点准备mysql，并测试nfs。以下步骤，各节点一致。
node1配置
[root@node1 ~]# mkdir /mydata [root@node1 ~]# showmount -e 192.168.0.20
Export list for 192.168.0.20:
/mydata 192.168.0.0/
[root@node1 ~]# mount -t nfs 192.168.0.20:/mydata /mydata
[root@node1 ~]# mount | grep /mydata
192.168.0.20:/mydata on /mydata type nfs (rw,vers=,addr=192.168.0.20,clientaddr=192.168.0.15) [root@node1 ~]# groupadd -r -g mysql
[root@node1 ~]# useradd -r -g -u mysql #验证mysql用户是否拥有共享目录权限
[root@node1 ~]# su - mysql
su: warning: cannot change directory to /home/mysql: No such file or directory
-bash-4.1$
-bash-4.1$
-bash-4.1$ cd /mydata/data
-bash-4.1$ touch node1.txt
-bash-4.1$ ls
node1.txt
-bash-4.1$ rm node1.txt
-bash-4.1$ exit
logout #在nfs server端验证
[root@node3 ~]# cd /mydata/data
[root@node3 data]# ll
total
-rw-rw-r--. mysql mysql Nov : node2.txt #验证root用户对目录是否有权限
[root@node2 ~]# touch /mydata/data/node.txt
[root@node2 ~]# ll /mydata/data
total
-rw-r--r--. root root Nov : node.txt #安装mariadb
[root@node1 ~]# tar xf mariadb-5.5.-linux-x86_64.tar.gz -C /usr/local
[root@node1 ~]# cd /usr/local
[root@node1 local]# ln -sv mariadb-5.5.-linux-x86_64 mysql
`mysql' -> `mariadb-5.5.46-linux-x86_64'
[root@node1 local]# cd mysql/
[root@node1 mysql]# chown -R root.mysql ./* #初始化mysql至nfs，此步骤只需一个节点操作即可，本文node1执行，那么node2就不需要执行
#初始化操作后，可以将nfs server的共享选项中的no_root_squash移除了
[root@node1 mysql]# ./scripts/mysql_install_db --datadir=/mydata/data/ --user=mysql #nfs server验证
[root@node3 data]# ls
aria_log.00000001 aria_log_control mysql performance_schema test #为mysql节点准备配置文件
[root@node1 mysql]# mkdir /etc/mysql
[root@node1 mysql]# cp support-files/my-large.cnf /etc/mysql/my.cnf
#编辑配置文件，加入以下三行
[root@node1 mysql]# vim /etc/mysql/my.cnf
datadir = /mydata/data
innodb_file_per_table = on
skip_name_resolve = on #为mysql节点准备服务脚本，并禁止mysqld开机自启
[root@node1 mysql]# cp support-files/mysql.server /etc/rc.d/init.d/mysqld
[root@node1 mysql]# chkconfig --add mysqld
[root@node1 mysql]# chkconfig mysqld off #启动mysql，创建mydb数据库
[root@node1 mysql]# service mysqld start
[root@node1 mysql]# /usr/local/mysql/bin/mysql
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 3
Server version: 5.5.46-MariaDB-log MariaDB Server Copyright (c) 2000, 2015, Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MariaDB [(none)]> CREATE DATABASE mydb;
Query OK, 1 row affected (0.03 sec) MariaDB [(none)]> exit
Bye [root@node1 mysql]# service mysqld stop
node2配置
[root@node2 ~]# tar xf mariadb-5.5.-linux-x86_64.tar.gz -C /usr/local
[root@node2 ~]# cd /usr/local/
[root@node2 local]# ln -sv mariadb-5.5.-linux-x86_64 mysql
`mysql' -> `mariadb-5.5.46-linux-x86_64'
[root@node2 local]# cd mysql/
[root@node2 mysql]# chown root.mysql ./* #将node1的mysql配置文件复制给node2
[root@node1 mysql]# scp /etc/mysql/my.cnf node2:/etc/mysql/
#准备服务脚本，并禁止开机自启
[root@node2 mysql]# cp support-files/mysql.server /etc/rc.d/init.d/mysqld
[root@node2 mysql]# chkconfig --add mysqld
[root@node2 mysql]# chkconfig mysqld off #启动服务并查看共享数据库
[root@node2 mysql]# service mysqld start
[root@node2 mysql]# /usr/local/mysql/bin/mysql
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 2
Server version: 5.5.46-MariaDB-log MariaDB Server Copyright (c) 2000, 2015, Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MariaDB [(none)]> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mydb |
| mysql |
| performance_schema |
| test |
+--------------------+
5 rows in set (0.02 sec) MariaDB [(none)]> EXIT
Bye #授权root用户远程访问mysql
[root@node2 ~]# /usr/local/mysql/bin/mysql
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 3
Server version: 5.5.46-MariaDB-log MariaDB Server Copyright (c) 2000, 2015, Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MariaDB [(none)]> grant all on *.* to 'root'@'192.168.%.%' identified by '123456';
Query OK, 0 rows affected (0.06 sec) MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.01 sec) [root@node2 mysql]# service mysqld stop
在node1和node2卸载共享目录
[root@node1 mysql]# umount /mydata
三、在heartbeat-gui界面配置
1、添加组资源，以及ip资源
2、添加共享文件系统资源
3、添加mysql-server资源
注意：定义的次序就是启动的次序。