LVS+keepalived學(xué)習(xí) --主備

憂(yōu)郁_小剛 2011-04-25

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LVS+keepalived學(xué)習(xí) --主備

((2009-10-23 10:23:06)

上次做了LVS+keepalived的負(fù)載均衡，效果還不錯(cuò)，但是沒(méi)有做主備，這次補(bǔ)上：

安裝環(huán)境：環(huán)境 centos4.4

關(guān)閉avahi-daemon

service avahi-daemon stop

一共準(zhǔn)備四臺(tái)機(jī)器：

負(fù)載均衡機(jī)器：

主：192.168.2.158 #安裝lvs+keepalived

備：192.168.2.159 #安裝lvs+keepalived

VIP:192.168.2.188

real-server1：192.168.2.187 #僅執(zhí)行腳本

real-server2：192.168.2.189 #僅執(zhí)行腳本

安裝過(guò)程：

在192.168.2.159上安裝ipvsadm和keepalived，方法不再贅述，主要看keepalived的配置：

! Configuration File for keepalived

global_defs {

notification_email {
admin@xx.com #郵件地址，需要本機(jī)開(kāi)啟SMTP服務(wù)
}
notification_email_from root@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL2 #負(fù)載均衡器標(biāo)示：同一局域網(wǎng)內(nèi)，應(yīng)該是唯一的。
}

vrrp_sync_group VGM {
group {
VI_1
}
}

vrrp_instance VI_1 {
state BACKUP #設(shè)置為BACKUP，通過(guò)priority控制那臺(tái)提升為主。
interface eth0
virtual_router_id 51
priority 70
advert_int 5
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.2.188
}
}

virtual_server 192.168.2.188 80 {
delay_loop 6
lb_algo rr
lb_kind DR
persistence_timeout 50
protocol TCP

real_server 192.168.2.187 80 {
weight 3
TCP_CHECK {
nb_get_retry 3
delay_before_retry 3
connect_port 80
connect_timeout 3
}
}
real_server 192.168.2.189 80 {
weight 1
TCP_CHECK {
nb_get_retry 3
delay_before_retry 3
connect_port 80
connect_timeout 3

}
}
}
紅色標(biāo)記為需要修改的地方。

執(zhí)行/etc/init.d/keepalived start

附上備機(jī)keepalived的啟動(dòng)日志：

Oct 22 23:40:35 test1 Keepalived: Starting Keepalived v1.1.17 (10/22,2009)
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Using MII-BMSR NIC polling thread...
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Netlink reflector reports IP 192.168.2.187 added
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Registering Kernel netlink reflector
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Registering Kernel netlink command channel
Oct 22 23:40:35 test1 keepalived: keepalived startup succeeded
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Opening file '/etc/keepalived/keepalived.conf'.
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Configuration is using : 10675 Bytes
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Activating healtchecker for service [192.168.2.187:80]
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Activating healtchecker for service [192.168.2.189:80]
Oct 22 23:40:35 test1 Keepalived: Starting Healthcheck child process, pid=5387
Oct 22 23:40:35 test1 Keepalived_vrrp: Using MII-BMSR NIC polling thread...
Oct 22 23:40:35 test1 Keepalived_vrrp: Netlink reflector reports IP 192.168.2.187 added
Oct 22 23:40:35 test1 Keepalived_vrrp: Registering Kernel netlink reflector
Oct 22 23:40:35 test1 Keepalived: Starting VRRP child process, pid=5389
Oct 22 23:40:35 test1 Keepalived_vrrp: Registering Kernel netlink command channel
Oct 22 23:40:35 test1 Keepalived_vrrp: Registering gratutious ARP shared channel
Oct 22 23:40:35 test1 Keepalived_vrrp: Opening file '/etc/keepalived/keepalived.conf'.
Oct 22 23:40:35 test1 Keepalived_vrrp: Configuration is using : 37155 Bytes
Oct 22 23:40:35 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE
Oct 22 23:40:35 test1 Keepalived_vrrp: VRRP sockpool: [ifindex(2), proto(112), fd(10,11)]

當(dāng)停掉主負(fù)載均衡時(shí)，備機(jī)負(fù)載均衡的接管日志：

Oct 22 23:42:18 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
Oct 22 23:42:18 test1 Keepalived_vrrp: VRRP_Group(VGB) Syncing instances to MASTER state
Oct 22 23:42:23 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
Oct 22 23:42:23 test1 Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
Oct 22 23:42:23 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.2.188
Oct 22 23:42:23 test1 Keepalived_vrrp: Netlink reflector reports IP 192.168.2.188 added
Oct 22 23:42:23 test1 Keepalived_healthcheckers: Netlink reflector reports IP 192.168.2.188 added
Oct 22 23:42:28 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.2.188

當(dāng)重啟主負(fù)載均衡時(shí),備機(jī)負(fù)載均衡的日志：

Oct 22 23:43:18 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Received higher prio advert
Oct 22 23:43:18 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE
Oct 22 23:43:18 test1 Keepalived_vrrp: VRRP_Instance(VI_1) removing protocol VIPs.
Oct 22 23:43:18 test1 Keepalived_vrrp: VRRP_Group(VGB) Syncing instances to BACKUP state
Oct 22 23:43:18 test1 Keepalived_vrrp: Netlink reflector reports IP 192.168.2.188 removed
Oct 22 23:43:18 test1 Keepalived_healthcheckers: Netlink reflector reports IP 192.168.2.188 removed

以上就完成雙機(jī)熱備的Lvs+keepalived的負(fù)載均衡。

relserver上需要執(zhí)行的腳本：

[root@test1 ~]# more /usr/local/bin/lvs_real
#!/bin/sh
VIP=192.168.2.188 （直接路由模式的vip必須跟服務(wù)器對(duì)外提供服務(wù)的ip地址在同一個(gè)網(wǎng)段）
/etc/rc.d/init.d/functions
case "$1" in
start)
echo " start tunl port"
ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP up

（如果有多VIP，依次往下寫(xiě)）
echo "2">/proc/sys/net/ipv4/conf/all/arp_announce
echo "1">/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2">/proc/sys/net/ipv4/conf/lo/arp_announce
echo "1">/proc/sys/net/ipv4/conf/lo/arp_ignore
;;
stop)
echo " stop tunl port"
ifconfig lo:0 down
echo "0">/proc/sys/net/ipv4/conf/all/arp_announce
echo "0">/proc/sys/net/ipv4/conf/all/arp_ignore
echo "0">/proc/sys/net/ipv4/conf/lo/arp_announce
echo "0">/proc/sys/net/ipv4/conf/lo/arp_ignore
;;

*)
echo "Usage: $0 {start|stop}"
exit 1
esac

總結(jié)：只需在負(fù)載均衡機(jī)器上安裝ipvsadm和keepalived，并執(zhí)行keepalived啟動(dòng)。在real server機(jī)器上僅需開(kāi)啟本地回環(huán)地址（腳本）即可，不用安裝任何軟件。

經(jīng)驗(yàn)：千萬(wàn)不要將負(fù)載均衡機(jī)器和web服務(wù)器搭建在一起，雖然端口等都不沖突，但是會(huì)出現(xiàn)莫名其妙的問(wèn)題..

1.real server上未執(zhí)行此腳本時(shí)：
[root@linux keepalived]# ifconfig lo:0
lo:0 Link encap:Local Loopback
UP LOOPBACK RUNNING MTU:16436 Metric:1

2.real server上執(zhí)行此腳本后：

[root@linux keepalived]# /usr/local/bin/lvs_real start
start tunl port
[root@YuHao-linux keepalived]# ifconfig lo:0
lo:0 Link encap:Local Loopback
inet addr:192.168.2.188 Mask:255.255.255.255
UP LOOPBACK RUNNING MTU:16436 Metric:1
所以：

keepalive機(jī)器上不用執(zhí)行此腳本，因?yàn)樵趉eepalived.conf中已經(jīng)定義了vip地址，

而real server機(jī)器上必須執(zhí)行此腳本。將虛擬IP綁定在本機(jī)回環(huán)網(wǎng)卡上。

這里還需注意一下MAC地址的問(wèn)題（netseek）：
假如兩臺(tái)VS之間使用的互備關(guān)系，那么當(dāng)一臺(tái)VS接管LVS服務(wù)時(shí)，可能會(huì)網(wǎng)絡(luò)不通，這時(shí)因?yàn)槁酚善鞯腗AC緩存表里無(wú)法及時(shí)刷新MAC.關(guān)于vip這個(gè)地址的MAC地址還是替換的VS的MAC，有兩種解決方法，一種是修改新VS的MAC地
址，另一種是使用 send_arp /arpiing 命令.
以arping 命令為例.
/sbin/arping -I eth0 -c 3 -s ${vip}${gateway_ip} > /dev/null 2>&1
Eg:
/sbin/arping -I eth0 -c 3 -s 192.168.1.6192.168.1.1

如果采用Piranha/keealived方案切換的時(shí)候會(huì)內(nèi)置自動(dòng)發(fā)送 send_arp命令.UltraMonkey方案經(jīng)測(cè)試也會(huì)自動(dòng)發(fā)送此命令.如用 heartbeat方案,需要寫(xiě)一個(gè)send_arp 或者arping 相關(guān)的腳本當(dāng)作heartbeat 一個(gè)資源切換服務(wù)的時(shí)候自動(dòng)發(fā)送相關(guān)命令腳本.

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