基于Drbd+Corosync构建高可用Mysql服务器

***********************************************

一、准备实验环境

二、安装corosync+cman

三、Drbd的安装于配置

四、安装Mysql服务器

五、使用corosync+crm定义资源

六、测试mysql是否是高可用

************************************************

一、准备实验环境

1、服务器IP地址规划

Drbd1:172.16.10.3

Drbd1:172.16.10.4

2、服务器操作系统

Drbd1：Centos 6.4 x86_64

Drbd2：Centos 6.4 x86_64

3、修改主机名以及hosts文件

####drbd1 server############
sed -i 's@\(HOSTNAME=\).*@\1drbd1@g' /etc/sysconfig/network
hostname drbd1
[root@drbd1 ~]# echo "172.16.10.3 drbd1" >> /etc/hosts
[root@drbd1 ~]# echo "172.16.10.4 drbd2" >> /etc/hosts
[root@drbd1 ~]# ssh-keygen -t rs
[root@drbd1 ~]# ssh-copy-id -i .ssh/id_rsa.pub drbd2
[root@drbd1 ~]# scp /etc/hosts drbd2:/etc/
####drbd2 server############
sed -i 's@\(HOSTNAME=\).*@\1drbd2@g' /etc/sysconfig/network
hostname drbd2
[root@drbd2 ~]# ssh-keygen -t rsa
[root@drbd2 ~]# ssh-copy-id -i .ssh/id_rsa.pub drbd1

4、创建Drbd磁盘分区规划

在drbd1与drbd2上创建磁盘分区（sda3）大小为5G，相信这个对大家来说都很easy，此处就省略了。注意在Centos6系统上必须重启系统，内核才能读到分区信息

二、安装Corosync+Crm

1、安装Corosync

###########drbd1#############
[root@drbd1 ~]# yum install corosync -y
###########drbd2#############
[root@drbd2 ~]# yum install corosync -y

2、配置Corosync

[root@drbd1 ~]# cd /etc/corosync/
[root@drbd1 corosync]# cp corosync.conf.example corosync.conf
[root@drbd1 corosync]# vim corosync.conf
# Please read the corosync.conf.5 manual page
compatibility: whitetank
totem {
        version: 2
        secauth: off
        threads: 0
        interface {
# Please read the corosync.conf.5 manual page
compatibility: whitetank
totem {
        version: 2
        secauth: off
# Please read the corosync.conf.5 manual page
compatibility: whitetank
totem {
        version: 2
        secauth: on   #开启认证功能
        threads: 0
        interface {
                ringnumber: 0
                bindnetaddr: 172.16.0.0         #修改为本机的网络地址
                mcastaddr: 226.94.1.1
                mcastport: 5405
                ttl: 1
        }
}
logging {
        fileline: off
        to_stderr: no
        to_logfile: yes
        to_syslog: yes
        logfile: /var/log/cluster/corosync.log
        debug: off
        timestamp: on
        logger_subsys {
                subsys: AMF
                debug: off
        }
}
amf {
        mode: disabled
}
####添加以下几行
service {
  ver:  0
  name: pacemaker
  # use_mgmtd: yes
   }
   aisexec {
     user: root
       group:  root
}

3、生成节点间通信时用到的认证密钥文件并将秘钥以及配置文件copy到drbd2

[root@drbd1 corosync]# corosync-keygen
Corosync Cluster Engine Authentication key generator.
Gathering 1024 bits for key from /dev/random.
Press keys on your keyboard to generate entropy.
Writing corosync key to /etc/corosync/authkey.
[root@drbd1 corosync]# scp corosync.conf authkey drbd2:/etc/corosync/

4、为两个节点创建corosync生成的日志所在的目录

[root@drbd1 corosync]# mkdir -pv /var/log/cluster
[root@drbd1 corosync]# ssh drbd2 "mkdir -pv /var/log/cluster"

5、安装Crmsh

[root@drbd1 ~]# wget ftp://195.220.108.108/linux/opensuse/factory/repo/oss/suse/x86_64/crmsh-1.2.6-0.rc2.1.1.x86_64.rpm
[root@drbd1 ~]# wget ftp://195.220.108.108/linux/opensuse/factory/repo/oss/suse/noarch/pssh-2.3.1-6.1.noarch.rpm
[root@drbd1 ~]# yum localinstall --nogpgcheck crmsh*.rpm pssh*.rpm -y
[root@drbd1 ~]# scp crmsh-1.2.6-4.el6.x86_64.rpm pssh-2.3.1-6.1.noarch.rpm drbd2:/root/
[root@drbd1 ~]# ssh drbd2 "yum localinstall --nogpgcheck crmsh*.rpm pssh*.rpm -y"qid

6、启动Corosync

[root@drbd1 ~]# /etc/init.d/corosync start
#启动之后没有报错，启动节点2
[root@drbd1 ~]# ssh drbd2 "/etc/init.d/corosync start"

7、查看集群节点的启动状态

[root@drbd1 ~]# crm status
Last updated: Thu Sep 19 11:06:54 2013
Last change: Thu Sep 19 11:03:21 2013 via crmd on drbd1
Stack: classic openais (with plugin)
Current DC: drbd2 - partition with quorum
Version: 1.1.8-7.el6-394e906
2 Nodes configured, 2 expected votes
0 Resources configured.
Online: [ drbd1 drbd2 ]                  #drbd1与drbd2都在线
You have new mail in /var/spool/mail/root
[root@drbd1 ~]#

Drbd共有两部分组成：内核模块和用户空间的管理工具。其中drbd内核模块代码已经整合进Linux内核2.6.33以后的版本中，因此，如果您的内核版本高于此版本的话，你只需要安装管理工具即可；否则，您需要同时安装内核模块和管理工具两个软件包，并且此两者的版本号一定要保持对应。

目前适用CentOS 5的drbd版本主要有8.0、8.2、8.3三个版本，其对应的rpm包的名字分别为drbd, drbd82和drbd83，对应的内核模块的名字分别为kmod-drbd, kmod-drbd82和kmod-drbd83。而适用于CentOS 6的版本为8.4，其对应的rpm包为drbd和drbd-kmdl，但在实际选用时，要切记两点：drbd和drbd-kmdl的版本要对应；另一个是drbd-kmdl的版本要与当前系统的内容版本相对应。我们实验所用的平台为x86_64且系统为CentOS 6.4，因此需要同时安装内核模块和管理工具。我们这里选用最新的8.4的版本(drbd-8.4.3-33.el6.x86_64.rpm和drbd-kmdl-2.6.32-358.el6-8.4.3-33.el6.x86_64.rpm)，下载地址为ftp://rpmfind.net/linux/atrpms/，请按照需要下载。

三、Drbd的安装于配置

1、安装Drbd软件包

[root@drbd1 ~]# wget ftp://195.220.108.108/linux/atrpms/el6-x86_64/atrpms/stable/drbd-8.4.3-33.el6.x86_64.rpm
[root@drbd1 ~]# wget ftp://195.220.108.108/linux/atrpms/el6-x86_64/atrpms/stable/drbd-kmdl-2.6.32-358.6.2.el6-8.4.3-33.el6.x86_64.rpm
[root@drbd1 ~]# rpm -ivh drbd-8.4.3-33.el6.x86_64.rpm drbd-kmdl-2.6.32-358.el6-8.4.3-33.el6.x86_64.rpm
warning: drbd-8.4.3-33.el6.x86_64.rpm: Header V4 DSA/SHA1 Signature, key ID 66534c2b: NOKEY
Preparing...                ########################################### [100%]
   1:drbd-kmdl-2.6.32-358.el########################################### [ 50%]
   2:drbd                   ########################################### [100%]
[root@drbd1 ~]# scp drbd-* drbd2:/root/
drbd-8.4.3-33.el6.x86_64.rpm                                                            100%  283KB 283.3KB/s   00:00
drbd-kmdl-2.6.32-358.el6-8.4.3-33.el6.x86_64.rpm                                        100%  145KB 145.2KB/s   00:00
[root@drbd1 ~]# ssh drbd2 " rpm -ivh drbd-8.4.3-33.el6.x86_64.rpm drbd-kmdl-2.6.32-358.el6-8.4.3-33.el6.x86_64.rpm "
warning: drbd-8.4.3-33.el6.x86_64.rpm: Header V4 DSA/SHA1 Signature, key ID 66534c2b: NOKEY
Preparing...                ##################################################
drbd-kmdl-2.6.32-358.el6    ##################################################
drbd                        ##################################################
[root@drbd1 ~]#

2、修改Drbd的主配置文件为

[root@drbd1 ~]# vim /etc/drbd.d/global_common.conf
global {
        usage-count no;
        # minor-count dialog-refresh disable-ip-verification
}
common {
        protocol C;
        handlers {
                pri-on-incon-degr "/usr/lib/drbd/notify-pri-on-incon-degr.sh; /usr/lib/drbd/notify-emergency-reboot.sh; echo b > /proc/sysrq-trigger ; reboot -f";
                pri-lost-after-sb "/usr/lib/drbd/notify-pri-lost-after-sb.sh; /usr/lib/drbd/notify-emergency-reboot.sh; echo b > /proc/sysrq-trigger ; reboot -f";
                local-io-error "/usr/lib/drbd/notify-io-error.sh; /usr/lib/drbd/notify-emergency-shutdown.sh; echo o > /proc/sysrq-trigger ; halt -f";
                # fence-peer "/usr/lib/drbd/crm-fence-peer.sh";
                # split-brain "/usr/lib/drbd/notify-split-brain.sh root";
                # out-of-sync "/usr/lib/drbd/notify-out-of-sync.sh root";
                # before-resync-target "/usr/lib/drbd/snapshot-resync-target-lvm.sh -p 15 -- -c 16k";
                # after-resync-target /usr/lib/drbd/unsnapshot-resync-target-lvm.sh;
        }
        startup {
                #wfc-timeout 120;
                #degr-wfc-timeout 120;
        }
        disk {
                on-io-error detach;
                #fencing resource-only;
        }
        net {
                cram-hmac-alg "sha1";
                shared-secret "mydrbdlab";
        }
        syncer {
                rate 1000M;
        }
}

3、定义一个资源名称为drbd

[root@drbd1 ~]# vim /etc/drbd.d/web.res
resource drbd {
  on drbd1 {
    device    /dev/drbd0;
    disk      /dev/sda3;
    address   172.16.10.3:7789;
    meta-disk internal;
  }
  on drbd2 {
    device    /dev/drbd0;
    disk      /dev/sda3;
    address   172.16.10.4:7789;
    meta-disk internal;
  }
}

4、将配置文件copy到Drbd2

[root@drbd1 ~]# cd /etc/drbd.d/
[root@drbd1 drbd.d]# scp global_common.conf web.res drbd2:/etc/drbd.d/
global_common.conf                                                                      100% 1401     1.4KB/s   00:00
web.res                                                                                 100%  266     0.3KB/s   00:00
[root@drbd1 drbd.d]#

5、在两个节点上初始化已 定义的资源并启动服务

[root@drbd1 ~]# drbdadm create-md drbd
NOT initializing bitmap
Writing meta data...
initializing activity log
New drbd meta data block successfully created.
lk_bdev_save(/var/lib/drbd/drbd-minor-0.lkbd) failed: No such file or directory
lk_bdev_save(/var/lib/drbd/drbd-minor-0.lkbd) failed: No such file or directory
[root@drbd1 ~]# ssh drbd2 "drbdadm create-md drbd"
NOT initializing bitmap
Writing meta data...
initializing activity log
New drbd meta data block successfully created.
lk_bdev_save(/var/lib/drbd/drbd-minor-0.lkbd) failed: No such file or directory
lk_bdev_save(/var/lib/drbd/drbd-minor-0.lkbd) failed: No such file or directory
[root@drbd1 ~]#/etc/init.d/drbd start
[root@drbd2 ~]# /etc/init.d/drbd start

6、查看Drbd状态信息

[root@drbd1 ~]# drbd-overview
  0:drbd/0  Connected Secondary/Secondary Inconsistent/Inconsistent C r-----
[root@drbd1 ~]#

从上面的信息中可以看出此时两个节点均处于Secondary状态。于是，我们接下来需要将其中一个节点设置为Primary。

7、设置drbd的节点为主节点

[root@drbd1 ~]# drbdadm primary --force drbd
[root@drbd1 ~]# drbd-overview #查看开始同步数据
  0:drbd/0  SyncSource Primary/Secondary UpToDate/Inconsistent C r-----
    [>....................] sync'ed:  2.9% (4984/5128)M
[root@drbd1 ~]# drbd-overview  #在此查看同步完成
  0:drbd/0  Connected Primary/Secondary UpToDate/UpToDate C r-----
[root@drbd1 ~]#

8、创建文件系统并格式化

[root@drbd1 ~]# mkdir -pv /mydata
[root@drbd1 ~]# mkfs.ext4 /dev/drbd0

9、挂载文件系统，查看状态

[root@drbd1 ~]# mount /dev/drbd0 /mydata/
[root@drbd1 ~]# drbd-overview
  0:drbd/0  Connected Primary/Secondary UpToDate/UpToDate C r----- /mydata ext4 5.0G 139M 4.6G 3%
[root@drbd1 ~]#

四、安装Mysql服务器

1、drbd1上安装（drbd主节点）

[root@drbd1 ~]# useradd -r -u 306 mysql
[root@drbd1 ~]# tar xf mysql-5.5.33-linux2.6-x86_64.tar.gz -C /usr/local/
[root@drbd1 ~]# cd /usr/local/
[root@drbd1 local]# ln -sv mysql-5.5.33-linux2.6-x86_64/ mysql
`mysql' -> `mysql-5.5.33-linux2.6-x86_64/'
[root@drbd1 local]# cd mysql
[root@drbd1 mysql]# chown root.mysql -R *
[root@drbd1 mysql]# ./scripts/mysql_install_db --user=mysql --datadir=/mydata/data/
[root@drbd1 mysql]# cp support-files/my-large.cnf /etc/my.cnf
[root@drbd1 mysql]# cp support-files/mysql.server /etc/init.d/mysqld
[root@drbd1 mysql]# vim /etc/my.cnf
thread_concurrency = 8
datadir=/mydata/data    #指定数据目录
[root@drbd1 mysql]# stervice mysqld start

注意：安装mysql（drbd2）之前需要卸载文件系统并降级

[root@drbd1 mysql]#start mysqld stop
[root@drbd1 mysql]# umount /mydata/
[root@drbd1 mysql]# drbdadm secondary drbd    #资源降级

2、drbd2安装

[root@drbd2 ~]# useradd -r -u 306 mysql
[root@drbd2 ~]# drbdadm primary drbd
[root@drbd2 ~]# mkdir -pv /mydata/
[root@drbd2 ~]# chown -R mysql.mysql /mydata/
[root@drbd2 ~]# mount /dev/drbd0 /mydata/
[root@drbd2 ~]#useradd -r -u 306 mysql
[root@drbd2 ~]#tar xf mysql-5.5.33-linux2.6-x86_64.tar.gz -C /usr/local/
[root@drbd2 ~]# cd /usr/local/
[root@drbd2 local]# ln -sv mysql-5.5.33-linux2.6-x86_64/ mysql
[root@drbd2 local]#cd mysql
[root@drbd2 mysql]# chown root:mysql * -R
[root@nginx2 mysql]# cp support-files/my-large.cnf /etc/my.cnf
[root@nginx2 mysql]# cp support-files/mysql.server /etc/init.d/mysqld

3、注意要测试mysql是否能正常启动

[root@drbd2 ~]# mount /dev/drbd0 /mydata/
[root@drbd2 ~]#service mysqld start

如果启动正常将继续下面的操作

[root@drbd2 ~]#service mysqld stop
[root@drbd2 ~]#umount /mydata
[root@drbd2 ~]#chkconfig mysqld off
[root@drbd2 ~]#ssh drbd1 "chkconfig mysqld off"

五、使用corosync+crm定义资源

[root@drbd1 ~]# crm conf
crm(live)configure# property no-quorum-policy=ignore
crm(live)configure# commit
crm(live)configure# primitive webdrbd ocf:linbit:drbd params drbd_resource=drbd op monitor role=Master interval=10 timeout=20 op monitor role=Slave interval=20 timeout=20 op start timeout=240  op stop timeout=100
crm(live)configure# verify
crm(live)configure# master ms_webdrbd  webdrbd meta master-max="1" master-node-max="1" clone-max="2" clone-node-max="1" notify="true"
crm(live)configure# verify
crm(live)configure# commit
crm(live)configure# exit

注释：

行4：定义了drbd的资源，并设置状态监控

行9：定义了drbd主节点的资源，并设置了状态监控

1、查看资源的状态

[root@drbd1 ~]# crm status
Last updated: Thu Sep 19 15:49:41 2013
Last change: Thu Sep 19 15:49:31 2013 via cibadmin on drbd1
Stack: classic openais (with plugin)
Current DC: drbd1 - partition with quorum
Version: 1.1.8-7.el6-394e906
2 Nodes configured, 2 expected votes
2 Resources configured.
Online: [ drbd1 drbd2 ]
 Master/Slave Set: ms_webdrbd [webdrbd]
     Masters: [ drbd1 ]
     Slaves: [ drbd2 ]

如果出现上述的结果，表示正常，如有问题，请检查操作步骤，此时drbd已经可以自动主从切换了

1.1、测试节点是否能正常切换

[root@drbd1 ~]# crm node standby            #drbd成为备用节点
[root@drbd1 ~]# crm status
Last updated: Thu Sep 19 15:54:19 2013
Last change: Thu Sep 19 15:54:13 2013 via crm_attribute on drbd1
Stack: classic openais (with plugin)
Current DC: drbd1 - partition with quorum
Version: 1.1.8-7.el6-394e906
2 Nodes configured, 2 expected votes
2 Resources configured.
Node drbd1: standby
Online: [ drbd2 ]
 Master/Slave Set: ms_webdrbd [webdrbd]
     Masters: [ drbd2 ]                     #切换到drbd2上
     Stopped: [ webdrbd:1 ]
[root@drbd1 ~]#

[root@drbd1 ~]# crm node online          #drbd1上线
[root@drbd1 ~]# crm status
Last updated: Thu Sep 19 15:55:37 2013
Last change: Thu Sep 19 15:55:31 2013 via crm_attribute on drbd1
Stack: classic openais (with plugin)
Current DC: drbd1 - partition with quorum
Version: 1.1.8-7.el6-394e906
2 Nodes configured, 2 expected votes
2 Resources configured.
Online: [ drbd1 drbd2 ]
 Master/Slave Set: ms_webdrbd [webdrbd]
     Masters: [ drbd2 ]
     Slaves: [ drbd1 ]                #drbd1上线成功
[root@drbd1 ~]#

2、定义mysql资源并定义约束

[root@drbd1 ~]# crm confi
crm(live)configure# primitive mystore ocf:heartbeat:Filesystem params device="/dev/drbd0" directory="/mydata" fstype=ext4 op monitor interval=40 timeout=40 op start timeout=60 op stop timeout=60
crm(live)configure# verify
crm(live)configure# primitive myip ocf:heartbeat:IPaddr params ip="172.16.10.8" op monitor interval=20 timeout=20 on-fail=restart
crm(live)configure# verify
crm(live)configure# primitive myserver lsb:mysqld op monitor interval=20 timeout=20 on-fail=restart
crm(live)configure# verify
crm(live)configure# exit

注释：

行2：定义了文件系统资源，用于过载drbd，并设置监控时长

行6：定义虚拟IP，并设置监控

行8：定义mysql服务的资源，并设置监控时长

3、查看资源状态

[root@drbd1 ~]# crm status
Last updated: Thu Sep 19 16:05:58 2013
Last change: Thu Sep 19 16:05:19 2013 via cibadmin on drbd1
Stack: classic openais (with plugin)
Current DC: drbd1 - partition with quorum
Version: 1.1.8-7.el6-394e906
2 Nodes configured, 2 expected votes
5 Resources configured.
Online: [ drbd1 drbd2 ]
 Master/Slave Set: ms_webdrbd [webdrbd]
     Masters: [ drbd2 ]
     Slaves: [ drbd1 ]
 myip   (ocf::heartbeat:IPaddr):    Started drbd1
 mystore    (ocf::heartbeat:Filesystem):    Started drbd2
Failed actions:
    myserver_start_0 (node=drbd1, call=149, rc=1, status=complete): unknown error
    mystore_start_0 (node=drbd1, call=141, rc=1, status=complete): unknown error
    myserver_start_0 (node=drbd2, call=143, rc=1, status=complete): unknown error

此时出现了一点点小问题那么我们就解决

[root@drbd1 ~]# crm resource cleanup mystore
[root@drbd1 ~]# crm resource cleanup myserver

4、此时在查看资源状态，已然正常

[root@drbd1 ~]# crm status
Last updated: Thu Sep 19 16:07:39 2013
Last change: Thu Sep 19 16:07:31 2013 via crmd on drbd2
Stack: classic openais (with plugin)
Current DC: drbd1 - partition with quorum
Version: 1.1.8-7.el6-394e906
2 Nodes configured, 2 expected votes
5 Resources configured.
Online: [ drbd1 drbd2 ]
 Master/Slave Set: ms_webdrbd [webdrbd]
     Masters: [ drbd2 ]
     Slaves: [ drbd1 ]
 myip   (ocf::heartbeat:IPaddr):    Started drbd1
 myserver   (lsb:mysqld):   Started drbd2
 mystore    (ocf::heartbeat:Filesystem):    Started drbd2
[root@drbd1 ~]#

此时资源没有运行在同一个节点上，显然是不符合实际需要的我们通过定义排列约束，将所有资源运行在同一个节点上

crm(live)configure#  colocation mystore_with_ms_webdrbd inf: mystore ms_webdrbd:Master
crm(live)configure# verify
crm(live)configure# colocation myserver_with_mystore_with_myip inf: myserver mystore myip
crm(live)configure# verify
crm(live)configure#

5、再此查看是否运行中同一个节点上

[root@drbd1 ~]# crm status
Last updated: Thu Sep 19 16:18:20 2013
Last change: Thu Sep 19 16:17:52 2013 via cibadmin on drbd1
Stack: classic openais (with plugin)
Current DC: drbd1 - partition with quorum
Version: 1.1.8-7.el6-394e906
2 Nodes configured, 2 expected votes
5 Resources configured.
Online: [ drbd1 drbd2 ]
 Master/Slave Set: ms_webdrbd [webdrbd]
     Masters: [ drbd2 ]
     Slaves: [ drbd1 ]
 myip   (ocf::heartbeat:IPaddr):    Started drbd2
 myserver   (lsb:mysqld):   Started drbd2
 mystore    (ocf::heartbeat:Filesystem):    Started drbd2
[root@drbd1 ~]#

由上看出已然运行在同一节点上

6、此时资源之间并没有启动顺序，定义排列约束

crm(live)configure#  order ms_webdrbd_before_mystore inf: ms_webdrbd:promote mystore:start
crm(live)configure# show xml
crm(live)configure# verify
crm(live)configure# commit
crm(live)configure# show xml
crm(live)configure# order mystore_before_myserver inf: mystore:start myserver:start
crm(live)configure# verify
crm(live)configure# order myserver_before_myip  inf: myserver:start myip:start
crm(live)configure# verify
crm(live)configure# commit

六、测试mysql是否是高可用

1、模拟节点故障并查看状态

[root@drbd1 ~]# ssh drbd2 "crm node standby"   #将drbd2设置为备用节点
[root@drbd1 ~]# crm status
Last updated: Thu Sep 19 16:29:10 2013
Last change: Thu Sep 19 16:28:50 2013 via crm_attribute on drbd2
Stack: classic openais (with plugin)
Current DC: drbd1 - partition with quorum
Version: 1.1.8-7.el6-394e906
2 Nodes configured, 2 expected votes
5 Resources configured.
Node drbd2: standby
Online: [ drbd1 ]
 Master/Slave Set: ms_webdrbd [webdrbd]
     Masters: [ drbd1 ]           #资源已经转移
     Stopped: [ webdrbd:1 ]
 myip   (ocf::heartbeat:IPaddr):    Started drbd1      
 myserver   (lsb:mysqld):   Started drbd1
 mystore    (ocf::heartbeat:Filesystem):    Started drbd1
[root@drbd1 ~]#

2、模拟mysql服务出现故障

[root@drbd1 ~]# service mysqld stop
#####使用watch命令动态查看mysql端口####
[root@drbd1 ~]# watch "netstat -anpt | grep 3306"
Every 2.0s: netstat -anpt | grep 3306                                                             Thu Sep 19 17:17:45 2013
tcp        0      0 0.0.0.0:3306                0.0.0.0:*                   LISTEN  36400/mysqld

当mysql服务停止之后，corosync会自动启动mysql，实现了mysql的高可用！！！

总结：

为了保证实验的成功，提醒大家在创建mysql用户时应该保证在两台服务器的mysql用户的UID相同，以免导致Mysql服务不能启动；在定义资源约束时，一定要定义合理，不然有可能在资源转移的时候出现问题，导致资源不能启动。

本博客至此结束，如有问题，望大家多提宝贵意见。欢迎大家一起来探讨高可用的相关话题！！！