DRBD就是网络RAID1,可以通过网络同步两个主机上的硬盘，drbd每次只允许对一个节点进行读写访问。

CentOS 6.x

rpm -ivh http://www.elrepo.org/elrepo-release-6-6.el6.elrepo.noarch.rpm
yum -y install drbd83-utils kmod-drbd83

CentOS 7.x

rpm -ivh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm
yum install -y drbd84-utils kmod-drbd84

Ubuntu16.x

apt-get install drbd-utils

#同步时间

ntpdate -u asia.pool.ntp.org

#加载drbd到内核

modprobe drbd

#查看内核是否加载drbd
lsmod |grep drbd

#更改两台主机的主机名

在test1上执行

echo "test1" > /etc/hostname
echo "test1 172.16.80.25" >> /etc/hosts
echo "test2 172.16.80.26" >> /etc/hosts
hostname test1

在test2上执行

echo "test2" > /etc/hostname
echo "test1 172.16.80.25" >> /etc/hosts
echo "test2 172.16.80.26" >> /etc/hosts
hostname test2 

cd /etc/drbd.d/

vim global_common.conf

global {
usage-count no;
}

common {
protocol C;
handlers {
}

startup {  
}

options {  
}

disk {  
     on-io-error detach;  
}

net {  
    cram-hmac-alg "sha1";  
        shared-secret "mydrbdtjiyu";  
}  
syncer {  
    rate 1024M;  
}  

}

vim mydrbd.res

resource mydrbd {
on test1 {
device /dev/drbd0;
disk /dev/sdb1;
address 172.16.80.25:;
meta-disk internal;
}
on test2 {
device /dev/drbd0;
disk /dev/sdb1;
address 172.16.80.26:;
meta-disk internal;
}
}

复制这两份配置文件到test1、test2

service drbd start

dd if=/dev/zero of=/dev/sdb1 bs=1M count=100

fdisk /dev/sdb

n-p-1-回车-回车-w

#激活资源mydrbd

drbdadm create-md mydrbd

#创建挂载点

mkdir /mnt/drbd

#在主上格式磁盘，挂载并写入文件

drbdsetup /dev/drbd0 primary
mkfs.ext4 /dev/drbd0
mount /dev/drbd0 /mnt/drbd

主备切换查看同步情况

cat /proc/drbd

主备手动切换方法：

1.先将主上面的磁盘卸载掉并降级
umount /dev/drbd0
drbdadm secondary r0

2.在备机上升级为主机
drbdadm primary r0

3.挂载磁盘
mount /dev/drbd0 /media/mnt

https://www.dwhd.org/20150523_150831.html

https://www.cnblogs.com/wsl222000/p/5777382.html

https://www.linuxprobe.去掉com/centos6-drdb-setup-instal.html?jimmo2370