2.添加新的slave接口

我们现在可以将新的从接口 em2 添加到绑定。

# ifenslave bond0 em2

众所周知，接口绑定在提供容错和增加带宽方面非常有用。
我们可以在不中断生产工作的情况下更改bonding的主动从接口。
在下面的例子中，我们有 2 个从属接口 em0 和 em1（em1 是活动从站）的接口绑定 bond0。
我们将用新的从接口 em2 替换从接口 em0。

# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
Bonding Mode: fault-tolerance (active-backup)
Primary Slave: None
Currently Active Slave: em0
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 5000
Down Delay (ms): 5000
Slave Interface: em0
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 00:21:28:b2:65:26
Slave queue ID: 0
Slave Interface: em1
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 00:21:28:b2:65:27
Slave queue ID: 0

3.分离旧的slave接口

一旦我们添加了一个新的从接口，我们就可以分离旧的从接口并将其从绑定中移除。

# ifenslave -d bond0 em0

4. 验证

确认新的从设备现在是绑定中的备用接口。

# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
Bonding Mode: fault-tolerance (active-backup)
Primary Slave: None
Currently Active Slave: em1
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 5000
Down Delay (ms): 5000
Slave Interface: em1
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 00:21:28:b2:65:27
Slave queue ID: 0
Slave Interface: em2
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 00:29:3a:c1:63:71
Slave queue ID: 0

1.将活动从机改为em1

ifenslave 命令可用于从绑定中添加或者分离或者更改当前活动的从接口。
现在，将活动从接口更改为 em1.

# ifenslave -c bond0 em1

再次检查绑定状态以确保 em1 是新的活动从站：

# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
Bonding Mode: fault-tolerance (active-backup)
Primary Slave: None
Currently Active Slave: em1
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 5000
Down Delay (ms): 5000
Slave Interface: em0
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 00:21:28:b2:65:26
Slave queue ID: 0
Slave Interface: em1
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 00:21:28:b2:65:27
Slave queue ID: 0

主动从机的切换应该立即生效，但在关键生产系统上，请先安排维护窗口或者在相同的测试环境中进行一些测试。

使更改永久化

我们刚刚所做的更改是暂时的，将在服务器重新启动后清除。
为了使这些更改永久化，我们将不得不做一些更改。

确保删除文件 /etc/sysconfig/network-scripts/ifcfg-em0，因为我们不再在绑定中使用此接口。
在bonding中为新的slave接口创建一个新文件：

# rm /etc/sysconfig/network-scripts/ifcfg-em0

# vi /etc/sysconfig/network-scripts/ifcfg-em2
DEVICE=em2
BOOTPROTO=none
ONBOOT=yes
MASTER=bond0
SLAVE=yes