Distributed Replicated Block Device(DRBD)是一个用软件实现的、无共享的、服务器之间镜像块设备内容的存储复制解决方案。数据镜像：实时、透明、同步（所有服务器都成功后返
回）、异步（本地服务器成功后返回）。DRBD的核心功能通过Linux的内核实现，最接近系统的IO栈，但它不能神奇地添加上层的功能比如检测到EXT3文件系统的崩溃。DRBD的位置处于
文件系统以下，比文件系统更加靠近操作系统内核及IO栈。
一、安装环境说明
- 系统版本：CentOS6.5
- DRBD版本：DRBD-8.4.3
- node1: 192.168.7.88（drbd1)
- node2: 192.168.7.89 (drbd2)
- (node1)为仅主节点配置
- (node2)为仅从节点配置
- (node1,node2)为主从节点共同配置
二、准备环境：(node1,node2)
1.关闭iptables和SELINUX，避免安装过程中报错
- service iptables stop //关闭iptables
- setenforcing 0 //暂时关闭selinux
- sed -i 's/SELINUX=enforcing/SELINUX=disabled/' /etc/sysconfig/selinux //永久关闭selinux
2.设置hosts文件
- vi /etc/hosts
- 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
- ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
- 192.168.7.88 drbd1
- 192.168.7.89 drbd2
3.在两台虚拟机上添加一块2G硬盘sdb作为DRBD，分别分区为sdb1，大小1G，并在本地系统创建/data目录，不做挂载操作。
- fdisk /dev/sdb
- ----------------
- n-p-1-回车-"+1G"-wq
- ----------------
- mkdir /data
4.时间同步：
1.安装依赖包：(node1,node2)
yum install gcc gcc-c++ make glibc flex kernel-devel kernel-headers
2.安装DRBD：(node1,node2)
- wget http://oss.linbit.com/drbd/8.4/drbd-8.4.3.tar.gz
- tar zxvf drbd-8.4.3.tar.gz
- cd drbd-8.4.3
- ./configure --prefix=/usr/local/drbd --with-km
- make && make install
- mkdir -p /usr/local/drbd/var/run/drbd
- cp /usr/local/drbd/etc/rc.d/init.d/drbd /etc/rc.d/init.d
- chkconfig --add drbd
- chkconfig drbd on
- 加载DRBD模块:
- modprobe drbd
- 查看DRBD模块是否加载到内核：
- lsmod |grep drbd
四、DRBD的配置
1.参数配置：(node1,node2)
- vim /usr/local/drbd/etc/drbd.conf
- 清空里面的配置，添加如下配置：
- resource r0{
- protocol C;
- startup { wfc-timeout 0; degr-wfc-timeout 120;}
- disk { on-io-error detach;}
- net{
- timeout 60;
- connect-int 10;
- ping-int 10;
- max-buffers 2048;
- max-epoch-size 2048;
- }
- syncer { rate 30M;}
- on drbd1.example.com{
- device /dev/drbd0;
- disk /dev/sdb1;
- address 192.168.7.88:7788;
- meta-disk internal;
- }
- on drbd2.example.com{
- device /dev/drbd0;
- disk /dev/sdb1;
- address 192.168.7.89:7788;
- meta-disk internal;
- }
- }
2.创建DRBD设备并激活r0资源：(node1,node2)
- mknod /dev/drbd0 b 147 0
- drbdadm create-md r0
- 等待片刻，显示success表示drbd块创建成功
- ----------------
- Writing meta data...
- initializing activity log
- NOT initializing bitmap
- New drbd meta data block successfully created.
- --== Creating metadata ==--
- As with nodes, we count the total number of devices mirrored by DRBD
- at http://usage.drbd.org.
- The counter works anonymously. It creates a random number to identify
- the device and sends that random number, along with the kernel and
- DRBD version, to usage.drbd.org.
- http://usage.drbd.org/cgi-bin/insert_usage.pl?
- nu=716310175600466686&ru=15741444353112217792&rs=1085704704
- * If you wish to opt out entirely, simply enter 'no'.
- * To continue, just press [RETURN] //出现[RETURN]按回车
- success
- ----------------
- 再次输入该命令：
- # drbdadm create-md r0
- 成功激活r0
- ----------------
- [need to type 'yes' to confirm] yes
- Writing meta data...
- initializing activity log
- NOT initializing bitmap
- New drbd meta data block successfully created.
3.启动DRBD服务：(node1,node2)
注：需要主从共同启动方能生效
4.查看状态：(node1,node2)
- cat /proc/drbd
- version: 8.4.3 (api:1/proto:86-101)
- GIT-hash: 89a294209144b68adb3ee85a73221f964d3ee515 build by root@drbd1.example.com,
- 2013-05-27 20:45:19
- 0: cs:Connected ro:Secondary/Secondary ds:Inconsistent/Inconsistent C r-----
- ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:1060184
- 或者
- service drbd status
- drbd driver loaded OK; device status:
- version: 8.4.3 (api:1/proto:86-101)
- GIT-hash: 89a294209144b68adb3ee85a73221f964d3ee515 build by root@drbd1.example.com,
- 2013-05-27 20:45:19
- m:res cs ro ds p mounted fstype
- 0:r0 Connected Secondary/Secondary Inconsistent/Inconsistent C
注：这里ro:Secondary/Secondary表示两台主机的状态都是备机状态，ds是磁盘状态，显示的状态内容为“不一致”，这是因为DRBD无法判断哪一方为主机，应以哪一方的磁盘数据作为标准。
5.将drbd1主机配置为主节点：(node1)
- drbdsetup /dev/drbd0 primary --force
分别查看主从DRBD状态：
- (node1)
- service drbd status
- drbd driver loaded OK; device status:
- version: 8.4.3 (api:1/proto:86-101)
- GIT-hash: 89a294209144b68adb3ee85a73221f964d3ee515 build by root@drbd1.example.com,
- 2013-05-27 20:45:19
- m:res cs ro ds p mounted fstype
- 0:r0 Connected Primary/Secondary UpToDate/UpToDate C
- (node2)
- service drbd status
- drbd driver loaded OK; device status:
- version: 8.4.3 (api:1/proto:86-101)
- GIT-hash: 89a294209144b68adb3ee85a73221f964d3ee515 build by root@drbd2.example.com,
- 2013-05-27 20:49:06
- m:res cs ro ds p mounted fstype
- 0:r0 Connected Secondary/PrimaryUpToDate/UpToDate C
注：ro在主从服务器上分别显示 Primary/Secondary和Secondary/Primary ds显示UpToDate/UpToDate表示主从配置成功。
6.挂载DRBD：(node1)
- 从刚才的状态上看到mounted和fstype参数为空，所以我们这步开始挂载DRBD到系统目录
- mkfs.ext4 /dev/drbd0
- mount /dev/drbd0 /data
- 注：Secondary节点上不允许对DRBD设备进行任何操作，包括只读，所有的读写操作只能
- 在Primary节点上进行，只有当Primary节点挂掉时，Secondary节点才能提升为Primary节点继续工作。
五、模拟故障
- (node1)
- cd /data
- touch 1 2 3 4 5
- cd ..
- umount /data
- drbdsetup /dev/drbd0 secondary
注：这里实际生产环境若DRBD1宕机，在DRBD2状态信息中ro的值会显示为Secondary/Unknown,
只需要进行DRBD提权操作即可。
(node2)
- drbdsetup /dev/drbd0 primary
- mount /dev/drbd0 /data
- cd /data
- touch 6 7 8 9 10
- ls
- --------------
- 1 10 2 3 4 5 6 7 8 9 lost+found
查看(node1)(node2)DRBD状态：
- (node2)
- service drbd status
- drbd driver loaded OK; device status:
- version: 8.4.3 (api:1/proto:86-101)
- GIT-hash: 89a294209144b68adb3ee85a73221f964d3ee515 build by root@drbd2.example.com,
- 2013-05-27 20:49:06
- m:res cs ro ds p mounted fstype
- 0:r0 Connected Primary/Secondary UpToDate/UpToDate C /data ext4
- (node1)
- service drbd status
- drbd driver loaded OK; device status:
- version: 8.4.3 (api:1/proto:86-101)
- GIT-hash: 89a294209144b68adb3ee85a73221f964d3ee515 build by root@drbd1.example.com,
- 2013-05-27 20:45:19
- m:res cs ro ds p mounted fstype
- 0:r0 Connected Secondary/Primary UpToDate/UpToDate C
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