MySQL主主復制+LVS+Keepalived實現MySQL高可用性
MySQL復制能夠保證數據的冗余的同時可以做讀寫分離來分擔系統壓力,如果是主主復制還可以很好的避免主節點的單點故障。但是MySQL主主復制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。
這篇文章下面要介紹如何通過LVS+Keepalived的方式來是實現MySQL的高可用性,同時解決以上問題。
Keepalived和LVS介紹
Keepalived 是一個基於 VRRP (虛擬路由冗余協議)可用來實現服務高可用性的軟件方案,避免出現單點故障。Keepalived一般用來實現輕量級高可用性,且不需要共享存儲,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服務器集群系統。本項目在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件項目之一。
LVS主要用於多服務器的負載均衡,作用於網絡層。LVS構建的服務器集群系統中,前端的負載均衡層被稱為Director Server;後端提供服務的服務器組層被稱為Real Server。通過下圖可以大致了解LVS的基礎架構。
LVS有三種工作模式,分別是DR(Direct Routing 直接路由)、TUN(Tunneling IP隧道)、NAT(Network Address Translation 網絡地址轉換)。其中TUN模式能夠支持更多的Real Server,但需要所有服務器支持IP隧道協議;DR也可以支持相當的Real Server,但需要保證Director Server虛擬網卡與物理網卡在同一網段;NAT擴展性有限,無法支持更多的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,影響效率。 同時,LVS負載均衡有10中調度算法,分別是rr、wrr、lc、wlc、lblc、lblcr、dh、sh、sed、nq
詳細的LVS說明請參見傳送門
本文中將利用LVS實現MySQL的讀寫負載均衡,Keepalived避免節點出現單點故障。
LVS+Keepalived配置
環境準備
LVS1:192.168.1.2
LVS2:192.168.1.11
MySQL Server1:192.168.1.5
MySQL Server2:192.168.1.6
VIP:192.168.1.100
OS: CentOS 6.4
Keepalive安裝
keepalived下載地址
需要安裝以下軟件包
# yum install -y kernel-devel openssl openssl-devel
解壓keepalived到/usr/local/並進入目錄執行配置編譯
# ./configure --prefix=/usr/local/keepalived --with-kernel-dir=/usr/src/kernels/2.6.32-431.5.1.el6.x86_64/ Keepalived configuration ------------------------ Keepalived version : 1.2.13 Compiler : gcc Compiler flags : -g -O2 Extra Lib : -lssl -lcrypto -lcrypt Use IPVS Framework : Yes IPVS sync daemon support : Yes IPVS use libnl : No fwmark socket support : Yes Use VRRP Framework : Yes Use VRRP VMAC : Yes SNMP support : No SHA1 support : No Use Debug flags : No # make && make install
默認情況下keepalived啟動時會去/etc/keepalived目錄下找配置文件,將需要的配置文件拷貝到指定位置
# cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/ # cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/ # cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/ # cp /usr/local/keepalived/sbin/keepalived /usr/sbin/ # chkconfig mysqld on # chkconfig keepalived on
LVS安裝
ipvsadm下載地址
需要安裝以下軟件包
# yum install -y libnl* popt*
查看是否加載lvs模塊
# modprobe -l |grep ipvs
解壓安裝
# ln -s /usr/src/kernels/2.6.32-431.5.1.el6.x86_64/ /usr/src/linux # tar -zxvf ipvsadm-1.26.tar.gz # make && make install
LVS安裝完成,查看當前LVS集群
# ipvsadm -L -n IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn
LVS+Keepalived配置
搭建MySQL主主復制
這裏不再贅述,請參考MySQL復制
配置Keepalived
下面是LVS1節點(Keepalived主節點)上的Keepalived配置,LVS2類似
# vim /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { router_id LVS1 } vrrp_instance VI_1 { state MASTER #指定instance初始狀態,實際根據優先級決定.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 #優先級,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 { 192.168.1.100 #VIP } } virtual_server 192.168.1.100 3306 { delay_loop 6 #服務輪詢的時間間隔 lb_algo wrr #加權輪詢調度,LVS調度算法 rr|wrr|lc|wlc|lblc|sh|sh lb_kind DR #LVS集群模式 NAT|DR|TUN,其中DR模式要求負載均衡器網卡必須有一塊與物理網卡在同一個網段 #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設置,3306就是MySQL連接端口 real_server 192.168.1.5 3306 { weight 3 ##權重 TCP_CHECK { connect_timeout 3 nb_get_retry 3 delay_before_retry 3 connect_port 3306 } } real_server 192.168.1.6 3306 { weight 3 TCP_CHECK { connect_timeout 3 nb_get_retry 3 delay_before_retry 3 connect_port 3306 } } }
配置LVS
編寫LVS啟動腳本/etc/init.d/realserver
#!/bin/sh VIP=192.168.1.100 . /etc/rc.d/init.d/functions case "$1" in # 禁用本地的ARP請求、綁定本地回環地址 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 #在回環地址上綁定VIP,設定掩碼,與Direct Server(自身)上的IP保持通信 /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腳本加入開機自啟動
# chmod +x /etc/init.d/realserver # echo "/etc/init.d/realserver" >> /etc/rc.d/rc.local
分別啟動LVS和keepalived
# service realserver start # service keepalived start
註意此時網卡的變化,可以看到虛擬網卡已經分配到了realserver上。
此時查看LVS集群狀態,可以看到集群下有兩個Real Server,調度算法,權重等信息。ActiveConn代表當前Real Server的活躍連接數
# ipvsadm -ln IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 192.168.1.100:3306 wrr persistent 50 -> 192.168.1.5:3306 Route 3 4 1 -> 192.168.1.6:3306 Route 3 0 2
此時LVS+Keepalived+MySQL主主復制已經搭建完成。
測試驗證
功能性驗證
關閉MySQL Server2
# service mysqld stop
在LVS1查看/var/log/messages中關於keepalived日誌,LVS1檢測到了MySQL Server2宕機,同時LVS集群自動剔除了故障節點
Sep 9 13:50:53 192.168.1.2 Keepalived_healthcheckers[18797]: TCP connection to [192.168.1.6]:3306 failed !!! Sep 9 13:50:53 192.168.1.2 Keepalived_healthcheckers[18797]: Removing service [192.168.1.6]:3306 from VS [192.168.1.100]:3306
從新啟動MySQL Server2後自動將故障節點自動加入LVS集群
Sep 9 13:51:41 192.168.1.2 Keepalived_healthcheckers[18797]: TCP connection to [192.168.1.6]:3306 success. Sep 9 13:51:41 192.168.1.2 Keepalived_healthcheckers[18797]: Adding service [192.168.1.6]:3306 to VS [192.168.1.100]:3306
關閉LVS1上的Keepalived(模擬宕機操作),查看LVS1上的日誌,可以看到Keepalived移出了LVS1上的VIP
Sep 9 14:01:27 192.168.1.2 Keepalived[18796]: Stopping Keepalived v1.2.13 (09/09,2014) Sep 9 14:01:27 192.168.1.2 Keepalived_healthcheckers[18797]: Removing service [192.168.1.5]:3306 from VS [192.168.1.100]:3306 Sep 9 14:01:27 192.168.1.2 Keepalived_healthcheckers[18797]: Removing service [192.168.1.6]:3306 from VS [192.168.1.100]:3306 Sep 9 14:01:27 192.168.1.2 Keepalived_vrrp[18799]: VRRP_Instance(VI_1) sending 0 priority Sep 9 14:01:27 192.168.1.2 Keepalived_vrrp[18799]: VRRP_Instance(VI_1) removing protocol VIPs.
同時查看LVS2上日誌,可以看到LVS2成為了Master,並接管了VIP
Sep 9 14:11:24 192.168.1.11 Keepalived_vrrp[7457]: VRRP_Instance(VI_1) Transition to MASTER STATE Sep 9 14:11:25 192.168.1.11 Keepalived_vrrp[7457]: VRRP_Instance(VI_1) Entering MASTER STATE Sep 9 14:11:25 192.168.1.11 Keepalived_vrrp[7457]: VRRP_Instance(VI_1) setting protocol VIPs. Sep 9 14:11:25 192.168.1.11 Keepalived_vrrp[7457]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.1.100 Sep 9 14:11:25 192.168.1.11 Keepalived_healthcheckers[7456]: Netlink reflector reports IP 192.168.1.100 added Sep 9 14:11:25 192.168.1.11 avahi-daemon[1407]: Registering new address record for 192.168.1.100 on eth0.IPv4. Sep 9 14:11:30 192.168.1.11 Keepalived_vrrp[7457]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.1.100
在LVS2上查看LVS集群狀態,一切正常。
# ipvsadm -ln IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 192.168.1.100:3306 wrr persistent 50 -> 192.168.1.5:3306 Route 3 2 0 -> 192.168.1.6:3306 Route 3 1 0
總結
- MySQL主主復制是集群的基礎,組成Server Array,其中每個節點作為Real Server。
- LVS服務器提供了負載均衡的作用,將用戶請求分發到Real Server,一臺Real Server故障並不會影響整個集群的。
- Keepalived搭建主備LVS服務器,避免了LVS服務器的單點故障,出現故障時可以自動切換到正常的節點。
MySQL主主復制+LVS+Keepalived實現MySQL高可用性