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corosync+pacemaker and drbd实现mysql高可用集群

DRBD：Distributed Replicated Block Device 分布式复制块设备，原理图如下

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

DRBD 有主双架构和双主架构的，当处于主从架构时，这个设备一定只有一个节点是可以读写的，另外的节点是不可读的，连挂载都不可能，只有一个节点是主的，其它节 点都是从的。当做为主主架构时，需要达到几个条件，1.在高可用集群中启用DRBD;  2. 启用分布式文件锁功能，即需要把磁盘格式化为集群文件系统（如GFS2，OCFS2等）；3. 把DRBD做成资源。

数据的存储过程： 当某个进程存储数据时在内核中通过DRBD模块复制一分通过TCP/IP套接字发送到从节点上去，从节点的DRBD在套接字上接收数据并通过DRBD模块 存储到磁盘，并把结果返回给主节点 。但是内核传输的速度很快，而TCP报文的传输速度相对来说要慢得多，于是会把数据存入TCP协议栈的发送缓冲区，然后从缓冲区慢慢传递到从节点上。这个 数据传输过程有三个模型：

A ： 异步模型，当内核把DRBD模块中复制的数据已经以报文方式发送到本地的TCP协议栈的缓冲区，至是从节点的数据是否已经传送到，保存是否完整，无法保证；

B ： 半同步模型，报文已经发送到从节点的套接字上，已经接收，并发往内核，但从节点的存储过程没有回应过程。

C：同步模型，报文发往从节点，从节点已经接收，并发往内核，内核已经把数据报文存储到磁盘，并把结果返回给主节点，这个是默认的数据传输模型，可以保证数据的完整性。

安装环境：

centos6.5,安装corosync和pacemaker过程请参见上一篇博客，上一个环境安装的配置接口是crmsh，这里安装的是pcs,安装pcs比较简单，#yum install pcs –y  即可

安装完成后集群状态如下：

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

现在看到两个集群节点mysql1 mysql2在线，pacemaker是做为插件在使用的，没有stonith设备，只有两个节点，所以quorum也要忽略

#pcs property set stonith-enabled=false

# pcs property set no-quorum-policy=ignore

#pcs config show                                               查看配置文件

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

显示错误还没有集群配置文件，stonith已经禁用，quorum已经忽略

安装drbd:

根据官方文档，drbd在内核2.6.33版本以后就已经装载进了内核，不需要再额外安装drbd，只需要安装drbdadm管理软件就行，我这里用的是centos6.5,内核版本是2.6.32，所以还需要安装

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

drbd版本有8.1 8.2 8.3 8.4,我这里用的是已经做好的rpm包进行安装，下载目录：ftp://rpmfind.net/linux/atrpms/

把drbd的两个rpm包放在/root目录下，然后执行# yum --nogpgcheck localinstall *.rpm

--nogpgcheck 不执行gpg检测,因为在centos里面没有认证文件

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

在两个节点上安装完成。加载DRBD模块

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[root@mysql1 ~]# modprobe drbd
[root@mysql1 ~]# lsmod | grep drbd
drbd                  325978  0
libcrc32c               1246  1 drbd
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创建一个新的磁盘分区做为DRBD的共享磁盘，我这里是xen虚拟机添加的一个磁盘/dev/xvdb,创建的磁盘为/dev/xvdb1
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[root@mysql1 drbd.d]# fdisk /dev/xvdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x218cde3e.
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 4 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 (1-4)
p
Partition number (1-4): 1
First cylinder (1-2610, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610):
Using default value 2610
 
Command (m for help): p
 
Disk /dev/xvdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x218cde3e
 
    Device Boot      Start         End      Blocks   Id  System
/dev/xvdb1               1        2610    20964793+  83  Linux
 
Command (m for help): w
The partition table has been altered!
 
Calling ioctl() to re-read partition table.
Syncing disks.

在mysql2节点上执行同样的操作。

配置drbd:

在/etc目录下有一个文件drbd.conf 主配置文件，里面主要调用了/etc/drbd.d/目录下的配置文件

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

配置/etc/drbd.d/global_common.conf

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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;
    }#这个配置文件主要是防止脑裂的发生
 
    startup {
        # wfc-timeout degr-wfc-timeout outdated-wfc-timeout wait-after-sb
                wfc-timeout 120;
                degr-wfc-timeout 120;  
}
 
    options {
        # cpu-mask on-no-data-accessible
    }
 
    disk {
            on-io-error detach;
                #fencing resource-only;
        }
 
    net {
                cram-hmac-alg "sha1";
                shared-secret "drbd1";
    }
        syncer {
                rate 1000M;
        }
}

在/etc/drbd.d/目录下再创建一个磁盘的资源

#vim /etc/drbd.d/stone.res

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resource mysql{
  on mysql1 {
    device    /dev/drbd0;
    disk      /dev/xvdb1;
    address   10.204.80.86:7789;
    meta-disk internal;
  }
  on mysql2 {
    device    /dev/drbd0;
    disk      /dev/xvdb1;
    address   10.204.80.85:7789;
    meta-disk internal;
  }
}

把这两个文件复制到mysql2节点上

然后在两个节点上初始化资源，分别执行

#drbdadm create-md mysql                                                           --这个资源是在stone.res文件中定义的资源

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

显示初始化成功

启动drbd服务

#service drbd start

查看drbd状态

#cat /proc/drbd

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

上面的信息两个节点都处于Secondary 状态，将mysql1节点设置为Primary

#drbdadm  primary  --force mysql

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

如上所示，数据同步过程已经开始，过一段时间后查看drbd状态

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

显示资源已经是主从状态

创建文件系统：

#mke2fs –t ext4 –L drbd /dev/drbd0                  #格式化为ext4文件系统，并指定label名为drbd

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

创建/data目录，并挂载分区

#mkdir /data

#mount /dev/drbd0 /data

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

挂载成功

在/data目录中创建 a,b,c,d四个文件，然后再手动切换Primary/Secondary节点

在节点mysql1上执行

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#cd /data && touch {a,b,c,d}
 
#umount /data
 
#drbdadm secondary mysql

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

可以看到drbd的状态又重新变为secondary /secondary状态

在mysql2节点上把drbd节点设置为Primary 状态，创建/data 目录 ，并挂载

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#drbdadm primary mysql
 
#cat /proc/drbd
 
#mkdir /data
 
#mount /dev/drbd0 /data
 
#ls /data

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

可以看到在mysql1节点上创建的a,b,c,d四个文件在mysql2节点上依然存在，drbd共享存储已经Ok

安装mysql，创建集群资源，安装mysql过程略

配置资源资源

pcs创建资源可以用 #pcs ？ 可以查看帮助信息

# pcs resource create mysqlip ipaddr ip=10.204.80.89 cidr_netmask=24 nic=eth0

添加DRBD资源，提供drbd的RA目前由OCF归类为linbit，其路径为/usr/lib/ocf/resource.d/linbit /drbd。drbd 需要同时运行在两个节点上，但只能有一个节点（primary/secondary模型）是Master，而另一个节点为Slave；因此，它是一种比较 特殊的集群资源，其资源类型为多状态（Multi-state）clone类型，即主机节点有Master和Slave之分，且要求服务刚启动时两个节点 都处于slave状态。

#pcs resource create  primitive mysqldrbd ocf:linbit:drbd params drbd_resource=mysql op monitor role=Master interval=50s timeout=30s op monitor role=Slave interval=60s timeout=30s  op start timeout=240 op stop timeout=100

或者#crm configure primitive mysqldrbd ocf:linbit:drbd params drbd_resource=mysql op monitor role=Master interval=10s timeout=20s op monitor role=Slave interval=20s timeout=20s op start timeout=240 op stop timeout=100

#pcs resource master ms_mysqldrbd mysqldrbd meta master-max="1" master-node-max="1" clone-max="2" clone-node-max="1" notify="true"

或者#crm configure ms ms_myqldrbd mysqldrbd  meta master-max="1" master-node-max="1" clone-max="2" clone-node-max="1" notify="true"

把drbd定义为clone资源，查看资源状态#pcs resource show

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

但做为文件系统还需要挂载，把drbd挂载到/data目录

# pcs resource create drbdfs ocf:heartbeat:Filesystem params device="/dev/drbd0" directory="/data" fstype="ext4"

查看资源状态

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

文件系统挂载drbdfs必须和Master mysqldrbd在同一节点上，必须先启动mysqldrbd然后才能挂载drbdfs文件系统，所以必须定义资源约束

# pcs constraint colocation add  drbdfs with master MS_mysqldrbd

# pcs constraint order promote MS_mysqldrbd then drbdfs                    ###drbd的资源添加完成

# pcs resource create MySQLD lsb:mysqld op monitor interval=20 timeout=20 on-fail=restart ###添加MySQLD 服务资源完成，定义MySQLD的资源约束，必须drbdfs文件系统先挂载然后才能启动MySQLD服务

# pcs constraint order drbdfs then MySQLD

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

把mysqlip ，drbdfs 和MySQLD服务定义到同一个资源组

# pcs resource group add myservice mysqlip drbdfs MySQLD

查看资源状态

corosync+pacemaker and drbd实现mysql高可用集群-LMLPHP

定义资源组的约束

#pcs constraint order mysqlip then promote MS_mysqldrbd then drbdfs then MySQLD

查看集群的配置信息

#pcs config show

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root@mysql1 /]# pcs config show
Cluster Name:
Corosync Nodes:
  
Pacemaker Nodes:
 mysql1 mysql2
 
Resources:
 Master: ms_mysqldrbd
  Meta Attrs: master-max=1 master-node-max=1 clone-max=2 clone-node-max=1 notify=true
  Resource: mysqldrbd (class=ocf provider=linbit type=drbd)
   Attributes: drbd_resource=mysql
   Operations: monitor interval=50s role=Master timeout=30s (mysqldrbd-monitor-interval-50s-role-Master)
               monitor interval=60s role=Slave timeout=30s (mysqldrbd-monitor-interval-60s-role-Slave)
 Group: myservice
  Resource: mysqlip (class=ocf provider=heartbeat type=IPaddr)
   Attributes: ip=10.204.80.89
   Operations: monitor interval=60s (mysqlip-monitor-interval-60s)
  Resource: drbdfs (class=ocf provider=heartbeat type=Filesystem)
   Attributes: device=/dev/drbd0 directory=/data fstype=ext4
   Operations: monitor interval=60s (drbdfs-monitor-interval-60s)
  Resource: MySQLD (class=lsb type=mysqld)
   Operations: monitor on-fail=restart interval=20 timeout=20 (MySQLD-monitor-interval-20)
 
Stonith Devices:
Fencing Levels:
 
Location Constraints:
Ordering Constraints:
  promote ms_mysqldrbd then start drbdfs (Mandatory) (id:order-ms_mysqldrbd-drbdfs-mandatory)
  start drbdfs then start MySQLD (Mandatory) (id:order-drbdfs-MySQLD-mandatory)
Colocation Constraints:
  drbdfs with ms_mysqldrbd (INFINITY) (rsc-role:Started) (with-rsc-role:Master) (id:colocation-drbdfs-ms_mysqldrbd-INFINITY-1)
 
Cluster Properties:
 cluster-infrastructure: classic openais (with plugin)
 dc-version: 1.1.10-14.el6_5.3-368c726
 expected-quorum-votes: 2
 no-quorum-policy: ignore
 stonith-enabled: false
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资源状态情况查看
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用其他机器连到10.204.80.89的mysql
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已经可以正常连接，把mysql1设置为standby
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发现mysql的集群已经正常转移，高可用集群正常

转载：http://piao719.blog.51cto.com/287547/1562390

04-30 22:17
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