技能展示:
- 了解LVS-DR群集的工作原理
- 会构建LVS-DR负载均衡群集
2.1 LVS-DR 集群
LVS-DR( Linux Virtual Server Director Server )工作模式,是生产环境中最常用的一种工作模式。
2.1.1.LVS-DR 工作原理
LVS-DR 模式, Director Server 作为群集的访问入口,不作为网关使用,节点 Director Server 与 Real Server 需要在同一个网络中,返回给客户端的数据不需要经过 Director Server。为了响应对整个群集的访问, Director Server 与 Real Server 都需要配置 VIP 地址,工作原理如图 2.1 所示。
图 2.1 DR 模式工作原理
2.1.2.数据包流向分析
以下为数据包流向分析步骤。
- 客户端发送请求到 Director Server,请求的数据报文(源 IP 是 CIP,目标 IP 是 VIP)到达内核空间。
- Director Server 和 Real Server 在同一个网络中,数据通过二层数据链路层来传输。
- 内核空间判断数据包的目标 IP 是本机 VIP,此时 IPVS 比对数据包请求的服务是否是集群服务,是集群服务就重新封装数据包。修改源 MAC 地址为 Director Server 的 MAC地址,修改目标 MAC 地址为 Real Server 的 MAC 地址,源 IP 地址与目标 IP 地址没有改变,然后将数据包发送给 Real Server。
- 到达 Real Server 的请求报文的 MAC 地址是自身的 MAC 地址,就接收此报文。数据包重新封装报文(源 IP 地址为 VIP,目标 IP 为 CIP),将响应报文通过 lo 接口传送给物理网卡然后向外发出。
- Real Server 直接将响应报文传送到客户端。
2.1.3.LVS-DR 模式特点
下面是 LVS-DR 模式的特点:
- Real Server 的网关不允许指向 Director Server IP,即不允许数据包经过 Director Server
- Director Server 和 Real Server 必须在同一个物理网络中。
- Real Server 可以使用私有地址,也可以使用公网地址。如果使用公网地址,可以通过互联网对 RIP 进行直接访问。
- 所有的请求报文经由 Director Server,但回复响应报文不能经过 Director Server。
- Real Server 上的 lo 接口配置 VIP 的 IP 地址。
2.2 案例:直接路由模式(LVS-DR)
2.2.1.准备案例环境
在 DR 模式的群集中, LVS 负载调度器作为群集的访问入口,但不作为网关使用;服务器池中的所有节点都各自接入 Internet ,发送给客户机的 Web 响应数据包不需要经过LVS 负载调度器,如图 2.2 所示。
这种方式入站、出站访问数据被分别处理,因此 LVS 负载调度器和所有的节点服务器都需要配置 VIP 地址,以便响应对整个群集的访问。考虑到数据存储的安全性,共享存储设备会放在内部的专用网络中。
图 2.2 基于 DR 模式的 LVS 负载均衡群集
2.2.2.配置负载调度器
下面是 配置负载调度器的具体步骤。
1. 配置虚拟 IP 地址(VIP)
采用虚接口的方式(ens33 ∶ 0 ),为网卡 ens33 绑定 VIP 地址,以便响应群集访问。配置结果为 ens33 192.168.8.10/24 、 ens33 ∶ 0 192.168.8.100/24 。
[root@node0 ~]# cd /etc/sysconfig/network-scripts/
[root@node0 network-scripts]# cp ifcfg-ens33 ifcfg-ens33:0
[root@node0 network-scripts]# vim ifcfg-ens33:0
NAME=ens33:0
DEVICE=ens33:0
ONBOOT=yes
IPADDR=192.168.8.100
NETMASK=255.255.255.255
[root@node0 network-scripts]# ifup ifcfg-ens33:0
[root@node0 network-scripts]# ifconfig
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.8.10 netmask 255.255.255.0 broadcast 192.168.8.255
inet6 fe80::aa3a:d990:b5ee:10 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:5b:2b:c3 txqueuelen 1000 (Ethernet)
RX packets 816 bytes 88977 (86.8 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 641 bytes 72042 (70.3 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
ens33:0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.8.100 netmask 255.255.255.255 broadcast 192.168.8.100
ether 00:0c:29:5b:2b:c3 txqueuelen 1000 (Ethernet)
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Local Loopback)
RX packets 32 bytes 2592 (2.5 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 32 bytes 2592 (2.5 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255
ether 52:54:00:de:25:dd txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@node0 network-scripts]#
2. 调整/proc响应参数
-
对于 DR 群集模式来说,由于 LVS 负载调度器和各节点需要共用 VIP 地址,应该关闭 Linux 内核重定向参数响应
-
服务器不是一台路由器,那么它不会发送重定向,所以可以关闭该功能
[root@node0 network-scripts]# vim /etc/sysctl.conf
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.ens33.send_redirects = 0[root@node0 network-scripts]# sysctl -p
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.ens33.send_redirects = 0
[root@node0 network-scripts]#
3. 配置负载分配策略
[root@node0 ~]# modprobe ip_vs
[root@node0 ~]# cat /proc/net/ip_vs
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
[root@node0 ~]#
[root@node0 ~]# yum -y install ipvsadm
[root@node0 ~]# ipvsadm -v
ipvsadm v1.27 2008/5/15 (compiled with popt and IPVS v1.2.1)
[root@node0 ~]#
[root@node0 ~]# ipvsadm -A -t 192.168.8.100:80 -s rr
[root@node0 ~]# ipvsadm -a -t 192.168.8.100:80 -r 192.168.8.11:80 -g -w 1
[root@node0 ~]# ipvsadm -a -t 192.168.8.100:80 -r 192.168.8.12:80 -g -w 1
[root@node0 ~]# ipvsadm-save > /etc/sysconfig/ipvsadm
[root@node0 ~]# cat /etc/sysconfig/ipvsadm
-A -t node0:http -s rr
-a -t node0:http -r 192.168.8.11:http -g -w 1
-a -t node0:http -r 192.168.8.12:http -g -w 1
[root@node0 ~]# systemctl start ipvsadm
[root@node0 ~]# systemctl enable ipvsadm
4. 配置存储服务器192.168.8.13
[root@node3 ~]# yum -y install nfs-utils rpcbind
[root@node3 ~]# mkdir -p /opt/wwwroot
[root@node3 ~]# vim /etc/exports
/opt/wwwroot 192.168.8.0/24(rw,sync,no_root_squash)
[root@node3 ~]# systemctl restart rpcbind
[root@node3 ~]# systemctl restart nfs
[root@node3 ~]# systemctl enable rpcbind
[root@node3 ~]# systemctl enable nfs
Created symlink from /etc/systemd/system/multi-user.target.wants/nfs-server.service to /usr/lib/systemd/system/nfs-server.service.
[root@node3 ~]# netstat -anpt | grep rpcbind
tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN 8004/rpcbind
tcp6 0 0 :::111 :::* LISTEN 8004/rpcbind
[root@node3 ~]#
5. 配置节点服务器192.168.8.11
[root@node1 ~]# yum -y install httpd
###配置虚拟IP地址
[root@node1 ~]# cd /etc/sysconfig/network-scripts/
[root@node1 network-scripts]# cp ifcfg-lo ifcfg-lo:0
[root@node1 network-scripts]# vim ifcfg-lo:0
DEVICE=lo
DEVICE=lo:0
IPADDR=192.168.8.100
NETMASK=255.255.255.255
ONBOOT=yes
[root@node1 network-scripts]# ifup lo:0
[root@node1 network-scripts]# ifconfig
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.8.11 netmask 255.255.255.0 broadcast 192.168.8.255
inet6 fe80::7457:78b3:7f51:9a01 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:6c:32:f2 txqueuelen 1000 (Ethernet)
RX packets 21487 bytes 29790262 (28.4 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 2877 bytes 246265 (240.4 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Local Loopback)
RX packets 32 bytes 2592 (2.5 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 32 bytes 2592 (2.5 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo:0: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 192.168.8.100 netmask 255.255.255.255
loop txqueuelen 1000 (Local Loopback)
virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255
ether 52:54:00:0b:33:85 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@node1 network-scripts]#
###调整/proc响应参数
[root@node1 network-scripts]# vim /etc/sysctl.conf
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
net.ipv4.conf.default.arp_ignore = 1
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
[root@node1 network-scripts]# sysctl -p
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
net.ipv4.conf.default.arp_ignore = 1
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
[root@node1 network-scripts]#
###配置httpd 挂载测试页
[root@node1 ~]# showmount -e 192.168.8.13
Export list for 192.168.8.13:
/opt/wwwroot 192.168.8.0/24
[root@node1 ~]#
[root@node1 ~]# mount 192.168.8.13:/opt/wwwroot /var/www/html/
[root@node1 ~]# vim /etc/fstab
192.168.8.13:/opt/wwwroot /var/www/html nfs defaults,_netdev 0 0
[root@node1 ~]# systemctl start httpd
[root@node1 ~]# systemctl enable httpd
Created symlink from /etc/systemd/system/multi-user.target.wants/httpd.service to /usr/lib/systemd/system/httpd.service.
[root@node1 ~]#
[root@node1 ~]# vim /var/www/html/index.html
<h1>www.bdqn.com</h1>
6. 配置节点服务器192.168.8.12
[root@node2 ~]# yum -y install httpd
###配置虚拟IP地址
[root@node2 ~]# cd /etc/sysconfig/network-scripts/
[root@node2 network-scripts]#
[root@node2 network-scripts]# cp ifcfg-lo ifcfg-lo:0
[root@node2 network-scripts]# vim ifcfg-lo:0
DEVICE=lo:0
IPADDR=192.168.8.100
NETMASK=255.255.255.255
ONBOOT=yes
[root@node2 network-scripts]# ifup lo:0
[root@node2 network-scripts]# ifconfig
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.8.12 netmask 255.255.255.0 broadcast 192.168.8.255
inet6 fe80::e986:8b82:f6f3:b650 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:59:ba:dd txqueuelen 1000 (Ethernet)
RX packets 22691 bytes 31861771 (30.3 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 3769 bytes 307582 (300.3 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Local Loopback)
RX packets 32 bytes 2592 (2.5 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 32 bytes 2592 (2.5 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo:0: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 192.168.8.100 netmask 255.255.255.255
loop txqueuelen 1000 (Local Loopback)
virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255
ether 52:54:00:7f:56:52 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@node2 network-scripts]#
###调整/proc响应参数
[root@node2 network-scripts]# vim /etc/sysctl.conf
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
net.ipv4.conf.default.arp_ignore = 1
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
[root@node2 network-scripts]# sysctl -p
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
net.ipv4.conf.default.arp_ignore = 1
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
[root@node2 network-scripts]#
###httpd 挂载测试页
[root@node2 ~]# showmount -e 192.168.8.13
Export list for 192.168.8.13:
/opt/wwwroot 192.168.8.0/24
[root@node2 ~]# mount 192.168.8.13:/opt/wwwroot /var/www/html
[root@node2 ~]# vim /etc/fstab
192.168.8.13:/opt/wwwroot /var/www/html/ nfs defaults,_netdev 0 0
[root@node2 ~]# systemctl start httpd
[root@node2 ~]# systemctl enable httpd