MySQL複製能夠保證資料的冗餘的同時可以做讀寫分離來分擔系統壓力，如果是主主複製還可以很好的避免主節點的單點故障。然而MySQL主主複製存在一些問題無法滿足我們的實際需要：未提供統一訪問入口來實現負載均衡，如果其中master宕掉的話需要手動切換到另外一個master，而不能自動進行切換。前面介紹了Mysql+Keepalived雙主熱備高可用方案記錄，那篇文件裡沒有使用到LVS（實現負載均衡），而下面要介紹的就是如何通過Keepalived+LVS方式來是實現MySQL的高可用性，利用LVS實現MySQL的讀寫負載均衡，Keepalived避免節點出現單點故障，同時解決以上問題。
Keepalived是一個基於VRRP（虛擬路由冗餘協議）可用來實現服務高可用性的軟體方案，避免出現單點故障。Keepalived一般用來實現輕量級高可用性，且不需要共享儲存，一般用於兩個節點之間，常見有LVS+Keepalived、Nginx+Keepalived組合。
LVS(Linux Virtual Server)是一個高可用性虛擬的伺服器叢集系統。本專案在1998年5月由章文嵩博士成立，是中國國內最早出現的自由軟體專案之一。LVS主要用於多伺服器的負載均衡，作用於網路層。LVS構建的伺服器叢集系統中，前端的負載均衡層被稱為Director Server；後端提供服務的伺服器組層被稱為Real Server。通過下圖可以大致瞭解LVS的基礎架構。
LVS有三種工作模式，分別是：
1）DR（Direct Routing 直接路由）模式。 DR可以支援相當多的Real Server，但需要保證Director Server（分發器）虛擬網路卡與物理網路卡在同一網段，並且後端Real Server的vip要建立在本地迴環口lo裝置上，這樣做是為了防止ip衝突；DR模式的好處是進站流量經過Director Server，出站流量不經過Director Server，減輕了Director Server的負載壓力。
2）NAT（Network Address Translation 網路地址轉換）模式。NAT擴充套件性有限，無法支援更多的Real Server，因為所有的請求包和應答包都需要Director Server進行解析再生，這樣就很影響效率。
3）TUN(Tunneling IP隧道）模式。TUN模式能夠支援更多的Real Server，但需要所有伺服器支援IP隧道協議；
LVS負載均衡有10中排程演算法，分別是：rr（輪詢）、wrr（加權輪詢）、lc、wlc、lblc、lblcr、dh、sh、sed、nq
以下詳細記錄了Mysql在主主同步環境下，利用LVS實現Mysql的讀寫負責均衡以及使用Keepalived心跳測試避免節點出現單點故障，實現故障轉移的高可用。
1）高可用方案的環境準備
LVS_Master： 182.148.15.237 LVS_Backup： 182.148.15.236 MySQL1 Real Server： 182.148.15.233 MySQL2 Real Server： 182.148.15.238 VIP： 182.148.15.239 OS: CentOS 6.8 溫馨提示：LVS_Master和LVS_Backup充當的是Director Server分發器的角色。 這裡的LVS採用DR模式，即"進站流量經過Director Server分發器，出站流量不經過分發器"，這就要求： 1）LVS_Master和LVS_Backup需要將VIP繫結在其正常提供服務的網路卡上（這裡指182.48.115.0網段所在的網路卡），netmask和對於網路卡裝置一致。 2）後端的Real Server要在本地迴環口lo上繫結vip（防止ip衝突）
2）環境部署記錄如下
a）Mysql主主熱備環境部署
MySQL1 Real Server1和MySQL2 Real Server的主主熱備可以參考Mysql+Keepalived雙主熱備高可用操作記錄中對應部分。
b）Keepalived安裝
LVS_Master和LVS_Backup的keepalived安裝，也可以參考Mysql+Keepalived雙主熱備高可用操作記錄中對應部分。
c）LVS安裝
LVS_Master和LVS_Backup兩臺機器安裝步驟一樣 首先開啟兩臺機器的ip_forward轉發功能 [root@LVS_Master ~]# echo "1" > /proc/sys/net/ipv4/ip_forward 先下載ipvsadm [root@LVS_Master ~]# cd /usr/local/src/ [root@LVS_Master src]# wget http://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.26.tar.gz 需要安裝以下軟體包 [root@LVS_Master src]# yum install -y libnl* popt* 檢視是否載入lvs模組 [root@LVS_Master src]# modprobe -l |grep ipvs 解壓安裝 [root@LVS_Master src]# ln -s /usr/src/kernels/2.6.32-431.5.1.el6.x86_64/ /usr/src/linux [root@LVS_Master src]# tar -zxvf ipvsadm-1.26.tar.gz [root@LVS_Master src]# cd ipvsadm-1.26 [root@LVS_Master ipvsadm-1.26]# make && make install LVS安裝完成，檢視當前LVS叢集 [root@LVS_Master ipvsadm-1.26]# ipvsadm -L -n IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn
d）編寫LVS啟動指令碼/etc/init.d/realserver
1）在MySQL1 Real Server伺服器上的操作
[root@MySQL1 ~]# vim /etc/init.d/realserver
#!/bin/sh
VIP=182.148.15.239
. /etc/rc.d/init.d/functions
case "$1" in
# 禁用本地的ARP請求、繫結本地迴環地址
start)
/sbin/ifconfig lo down
/sbin/ifconfig lo up
echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
/sbin/sysctl -p >/dev/null 2>&1
/sbin/ifconfig lo:0 $VIP netmask 255.255.255.255 up #在迴環地址上繫結VIP，設定掩碼，與Direct Server（自身）上的IP保持通訊
/sbin/route add -host $VIP dev lo:0
echo "LVS-DR real server starts successfully.\n"
;;
stop)
/sbin/ifconfig lo:0 down
/sbin/route del $VIP >/dev/null 2>&1
echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
echo "LVS-DR real server stopped.\n"
;;
status)
isLoOn=`/sbin/ifconfig lo:0 | grep "$VIP"`
isRoOn=`/bin/netstat -rn | grep "$VIP"`
if [ "$isLoON" == "" -a "$isRoOn" == "" ]; then
echo "LVS-DR real server has run yet."
else
echo "LVS-DR real server is running."
fi
exit 3
;;
*)
echo "Usage: $0 {start|stop|status}"
exit 1
esac
exit 0
將lvs指令碼加入開機自啟動
[root@MySQL1 ~]# chmod +x /etc/init.d/realserver
[root@MySQL1 ~]# echo "/etc/init.d/realserver" >> /etc/rc.d/rc.local
啟動LVS指令碼
[root@MySQL1 ~]# service realserver start
LVS-DR real server starts successfully.\n
檢視MySQL1 Real Server伺服器，發現VIP已經成功繫結到本地迴環口lo上了
[root@MySQL1 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 52:54:00:D1:27:75
inet addr:182.148.15.233 Bcast:182.148.15.255 Mask:255.255.255.224
inet6 addr: fe80::5054:ff:fed1:2775/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:598406 errors:0 dropped:0 overruns:0 frame:0
TX packets:12050 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:78790653 (75.1 MiB) TX bytes:33151764 (31.6 MiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:483 errors:0 dropped:0 overruns:0 frame:0
TX packets:483 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:55807 (54.4 KiB) TX bytes:55807 (54.4 KiB)
lo:0 Link encap:Local Loopback
inet addr:182.148.15.239 Mask:255.255.255.255
UP LOOPBACK RUNNING MTU:65536 Metric:1
2）在MySQL2 Real Server伺服器上的操作
[root@MySQL2 ~]# vim /etc/init.d/realserver //這個指令碼在後端Real Server上都是一樣的內容
#!/bin/sh
VIP=182.148.15.239
. /etc/rc.d/init.d/functions
case "$1" in
start)
/sbin/ifconfig lo down
/sbin/ifconfig lo up
echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
/sbin/sysctl -p >/dev/null 2>&1
/sbin/ifconfig lo:0 $VIP netmask 255.255.255.255 up
/sbin/route add -host $VIP dev lo:0
echo "LVS-DR real server starts successfully.\n"
;;
stop)
/sbin/ifconfig lo:0 down
/sbin/route del $VIP >/dev/null 2>&1
echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
echo "LVS-DR real server stopped.\n"
;;
status)
isLoOn=`/sbin/ifconfig lo:0 | grep "$VIP"`
isRoOn=`/bin/netstat -rn | grep "$VIP"`
if [ "$isLoON" == "" -a "$isRoOn" == "" ]; then
echo "LVS-DR real server has run yet."
else
echo "LVS-DR real server is running."
fi
exit 3
;;
*)
echo "Usage: $0 {start|stop|status}"
exit 1
esac
exit 0
將lvs指令碼加入開機自啟動並啟動lvs指令碼
[root@MySQL2 ~]# chmod +x /etc/init.d/realserver
[root@MySQL2 ~]# echo "/etc/init.d/realserver" >> /etc/rc.d/rc.local
[root@MySQL2 ~]# service realserver start
LVS-DR real server starts successfully.\n
[root@MySQL2 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 52:54:00:3B:33:8F
inet addr:182.148.15.238 Bcast:182.148.15.255 Mask:255.255.255.224
inet6 addr: fe80::5054:ff:fe3b:338f/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:135305 errors:0 dropped:0 overruns:0 frame:0
TX packets:11256 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:17338566 (16.5 MiB) TX bytes:892363 (871.4 KiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
lo:0 Link encap:Local Loopback
inet addr:182.148.15.239 Mask:255.255.255.255
UP LOOPBACK RUNNING MTU:65536 Metric:1
e）配置iptables防火牆
1）後端兩臺機器MySQL1 Real Server和MySQL2 Real Server要在iptables裡開放3306埠 [root@MySQL1 ~]# vim /etc/sysconfig/iptables ...... -A INPUT -m state --state NEW -m tcp -p tcp --dport 3306 -j ACCEPT [root@MySQL1 ~]# /etc/init.d/iptables restart 2）LVS_Master和LVS_Backup兩臺機器要在iptables開放VRRP組播地址的相關規則。 注意：這個一定要設定！！！否則會出現故障時的VIP資源漂移錯亂問題！ [root@LVS_Master ~]# vim /etc/sysconfig/iptables //兩臺LVS機器都要設定 ....... -A INPUT -s 182.148.15.0/24 -d 224.0.0.18 -j ACCEPT //允許組播地址通訊 -A INPUT -s 182.148.15.0/24 -p vrrp -j ACCEPT //允許VRRP（虛擬路由器冗餘協）通訊 -A INPUT -m state --state NEW -m tcp -p tcp --dport 3306 -j ACCEPT [root@LVS_Master ~]# /etc/init.d/iptables restart
3）接著配置LVS+Keepalived配置
1）LVS_Master上的操作
[root@LVS_Master ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
router_id LVS_Master
}
vrrp_instance VI_1 {
state MASTER #指定instance初始狀態，實際根據優先順序決定.backup節點不一樣
interface eth0 #虛擬IP所在網
virtual_router_id 51 #VRID，相同VRID為一個組，決定多播MAC地址
priority 100 #優先順序，另一臺改為90.backup節點不一樣
advert_int 1 #檢查間隔
authentication {
auth_type PASS #認證方式，可以是pass或ha
auth_pass 1111 #認證密碼
}
virtual_ipaddress {
182.148.15.239 #VIP
}
}
virtual_server 182.148.15.239 3306 {
delay_loop 6 #服務輪詢的時間間隔
lb_algo wrr #加權輪詢排程，LVS排程演算法 rr|wrr|lc|wlc|lblc|sh|sh
lb_kind DR #LVS叢集模式 NAT|DR|TUN，其中DR模式要求負載均衡器網路卡必須有一塊與物理網路卡在同一個網段
#nat_mask 255.255.255.0
persistence_timeout 50 #會話保持時間
protocol TCP #健康檢查協議
## Real Server設定，3306就是MySQL連線埠
real_server 182.148.15.233 3306 {
weight 3 ##權重
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
connect_port 3306
}
}
real_server 182.148.15.238 3306 {
weight 3
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
connect_port 3306
}
}
}
啟動keepalived
[root@LVS_Master ~]# /etc/init.d/keepalived start
Starting keepalived: [ OK ]
注意此時網路卡的變化，可以看到虛擬網路卡已經分配到了realserver上。
此時檢視LVS叢集狀態，可以看到叢集下有兩個Real Server，排程演算法，權重等資訊。ActiveConn代表當前Real Server的活躍連線數。
[root@LVS_Master ~]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 182.148.15.239:3306 wrr persistent 50
-> 182.148.15.233:3306 Route 3 1 0
-> 182.148.15.238:3306 Route 3 0 0
2）LVS_Backup上的操作
[root@LVS_Backup ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
router_id LVS_Backup
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 51
priority 90
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
182.148.15.239
}
}
virtual_server 182.148.15.239 3306 {
delay_loop 6
lb_algo wrr
lb_kind DR
persistence_timeout 50
protocol TCP
real_server 182.148.15.233 3306 {
weight 3
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
connect_port 3306
}
}
real_server 182.148.15.238 3306 {
weight 3
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
connect_port 3306
}
}
}
啟動keepalived
[root@LVS_Backup ~]# /etc/init.d/keepalived start
Starting keepalived: [ OK ]
[root@LVS_Backup ~]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 182.148.15.239:3306 wrr persistent 50
-> 182.148.15.233:3306 Route 3 0 0
-> 182.148.15.238:3306 Route 3 0 0
此時LVS+Keepalived+MySQL主主複製已經搭建完成。
4）最後進行測試驗證
1）先進行功能性驗證
a）關閉MySQL2 Real Server伺服器上的mysql
[root@MySQL2 ~]# /etc/init.d/mysql stop
Shutting down MySQL.. SUCCESS!
在LVS_Master檢視/var/log/messages中關於keepalived日誌，LVS_Master檢測到了MySQL2 Real Server伺服器當機，同時LVS叢集自動剔除了故障節點
[root@LVS_Master ~]# tail -f /var/log/messages
.......
Apr 26 15:22:19 test3-237 Keepalived_healthcheckers[4606]: TCP connection to [182.148.15.238]:3306 failed.
Apr 26 15:22:19 test3-237 Keepalived_vrrp[4608]: Sending gratuitous ARP on eth0 for 182.148.15.239
.......
[root@LVS_Master ~]# ipvsadm -ln //LVS已經將MySQL2 Real Server剔除
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 182.148.15.239:3306 wrr persistent 50
-> 182.148.15.233:3306 Route 3 1 0
從新啟動MySQL2 Real Server後自動將故障節點自動加入LVS叢集
[root@LVS_Master ~]# tail -f /var/log/messages
.......
Apr 26 15:23:49 test3-237 Keepalived_healthcheckers[4606]: TCP connection to [182.148.15.238]:3306 success.
Apr 26 15:23:49 test3-237 Keepalived_healthcheckers[4606]: Adding service [182.148.15.238]:3306 to VS [182.148.15.239]:3306
.......
[root@LVS_Master ~]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 182.148.15.239:3306 wrr persistent 50
-> 182.148.15.233:3306 Route 3 1 0
-> 182.148.15.238:3306 Route 3 1 0
b）關閉LVS_Master上的Keepalived（模擬當機操作），檢視LVS_Master上的日誌，可以看到Keepalived移出了LVS1上的VIP
[root@LVS_Master ~]# /etc/init.d/keepalived stop
Stopping keepalived: [ OK ]
[root@LVS_Master ~]# tail -f /var/log/messages
........
Apr 26 15:29:38 test3-237 Keepalived[4976]: Stopping
Apr 26 15:29:38 test3-237 Keepalived_vrrp[4979]: VRRP_Instance(VI_1) sent 0 priority
Apr 26 15:29:38 test3-237 Keepalived_vrrp[4979]: VRRP_Instance(VI_1) removing protocol VIPs.
Apr 26 15:29:38 test3-237 Keepalived_healthcheckers[4977]: Removing service [182.148.15.233]:3306 from VS [182.148.15.239]:3306
Apr 26 15:29:38 test3-237 Keepalived_healthcheckers[4977]: Removing service [182.148.15.238]:3306 from VS [182.148.15.239]:3306
Apr 26 15:29:38 test3-237 Keepalived_healthcheckers[4977]: Stopped
Apr 26 15:29:38 test3-237 kernel: IPVS: __ip_vs_del_service: enter
Apr 26 15:29:39 test3-237 Keepalived_vrrp[4979]: Stopped
Apr 26 15:29:39 test3-237 Keepalived[4976]: Stopped Keepalived v1.3.5 (03/19,2017), git commit v1.3.5-6-g6fa32f2
[root@LVS_Master ~]# ip addr //發現VIP資源已經不在本機了
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 52:54:00:68:dc:b6 brd ff:ff:ff:ff:ff:ff
inet 182.148.15.237/27 brd 182.148.15.255 scope global eth0
inet 182.148.15.239/27 brd 182.148.15.255 scope global secondary eth0:0
inet6 fe80::5054:ff:fe68:dcb6/64 scope link
valid_lft forever preferred_lft forever
同時檢視LVS_Backup上日誌，可以看到LVS_Backup成為了Master，並接管了VIP
[root@LVS_Backup ~]# tail -f /var/log/messages
.....
Apr 26 15:26:41 test4-236 Keepalived_vrrp[4711]: VRRP_Instance(VI_1) Transition to MASTER STATE
Apr 26 15:26:42 test4-236 Keepalived_vrrp[4711]: VRRP_Instance(VI_1) Entering MASTER STATE
Apr 26 15:26:42 test4-236 Keepalived_vrrp[4711]: VRRP_Instance(VI_1) setting protocol VIPs.
Apr 26 15:26:42 test4-236 Keepalived_vrrp[4711]: Sending gratuitous ARP on eth0 for 182.148.15.239
Apr 26 15:26:42 test4-236 Keepalived_vrrp[4711]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth0 for 182.148.15.239
[root@LVS_Backup ~]# ip addr //發現VIP資源已經轉移到LVS_Backup機器上了
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 52:54:00:90:ac:0f brd ff:ff:ff:ff:ff:ff
inet 182.148.15.236/27 brd 182.148.15.255 scope global eth0
inet 182.148.15.239/32 scope global eth0
inet6 fe80::5054:ff:fe90:ac0f/64 scope link
valid_lft forever preferred_lft forever
在LVS_Backup上檢視LVS叢集狀態，一切正常。
[root@LVS_Backup ~]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 182.148.15.239:3306 wrr persistent 50
-> 182.148.15.233:3306 Route 3 0 0
-> 182.148.15.238:3306 Route 3 1 1
接著恢復LVS_Master上的Keepalived，發現VIP資源又會重新從LVS_Backup上轉移回來。即LVS_Master重新接管服務。
[root@LVS_Master ~]# tail -f /var/log/messages
.......
Apr 26 15:37:14 test3-237 Keepalived_vrrp[5263]: VRRP_Instance(VI_1) Transition to MASTER STATE
Apr 26 15:37:15 test3-237 Keepalived_vrrp[5263]: VRRP_Instance(VI_1) Entering MASTER STATE
Apr 26 15:37:15 test3-237 Keepalived_vrrp[5263]: VRRP_Instance(VI_1) setting protocol VIPs.
Apr 26 15:37:15 test3-237 Keepalived_vrrp[5263]: Sending gratuitous ARP on eth0 for 182.148.15.239
Apr 26 15:37:15 test3-237 Keepalived_vrrp[5263]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth0 for 182.148.15.239
[root@LVS_Master ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 52:54:00:68:dc:b6 brd ff:ff:ff:ff:ff:ff
inet 182.148.15.237/27 brd 182.148.15.255 scope global eth0
inet 182.148.15.239/32 scope global eth0
inet 182.148.15.239/27 brd 182.148.15.255 scope global secondary eth0:0
inet6 fe80::5054:ff:fe68:dcb6/64 scope link
valid_lft forever preferred_lft forever
-----------------------------------------------------------------------------------------
2）接著進行mysql主主熱備的高可用
在MySQL1 Real Server和MySQL2 Real Server兩臺機器的mysql裡授權，使遠端客戶機能正常連線。
mysql> grant all on *.* to test@'%' identified by "123456";
Query OK, 0 rows affected (0.03 sec)
mysql> flush privileges;
經測試發現，對於上面的功能驗證，不管是LVS_Master的keepalived關閉（當機）還是後端MySQL2 Real Serve的mysql關閉，在遠端客戶機上都能正常連線mysql（通過VIP進行連線）（LVS_Master的keepalived關閉時，如若遠端客戶機在連線mysql中，可以斷開重新連線一次即可）
[root@bastion-IDC ~]# mysql -h182.148.15.239 -utest -p123456
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 856
Server version: 5.6.34-log Source distribution
Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> select * from huanqiu.haha;
+----+-----------+
| id | name |
+----+-----------+
| 1 | wangshibo |
| 2 | guohuihui |
| 22 | huihui |
| 23 | bobo |
+----+-----------+
4 rows in set (0.00 sec)
總結幾點：
1）MySQL主主複製是叢集的基礎，組成Server Array，其中每個節點作為Real Server。
2）LVS伺服器提供了負載均衡的作用，將使用者請求分發到Real Server，一臺Real Server故障並不會影響整個叢集的。
3）Keepalived搭建主備LVS伺服器，避免了LVS伺服器的單點故障，出現故障時可以自動切換到正常的節點。
4）VRRP虛擬IP地址和介面實際IP必須在同一個網段內，VRRP兩個實際介面不在同一網段，是不能形成主備關係的。因為：
VRRP的形式是組播（多播），這個和廣播基本一個原理，只不過縮小了範圍，讓幾個伺服器能收到，眾所周知廣播必須在2層裡面實現，出3層就出了廣播域了。 VRRP中的ip切換是靠arp欺騙實現的，否則vip從主切到備得斷多少機器，arp欺騙也是沒法在出了3層以外的2個機器直接做的。