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八种调度算法：
:rr|wrr|lc|wlc|lblc|dh|sh|
轮叫调度（Round-Robin Scheduling）
加权轮叫调度（Weighted Round-Robin Scheduling）
最小连接调度（Least-Connection Scheduling）
加权最小连接调度（Weighted Least-Connection Scheduling）
基于局部性的最少链接（Locality-Based Least Connections Scheduling）
带复制的基于局部性最少链接（Locality-Based Least Connections with Replication Scheduling）
目标地址散列调度（Destination Hashing Scheduling）
源地址散列调度（Source Hashing Scheduling）
三种均衡机制：
IP负载均衡技术是在负载调度器的实现技术中效率最高的。
三种机制分别是：
Virtual Server via Network Address Translation （VS/NAT）： 也有说端口映射的，其目标是将一组服务器构成一个高性能的、高可用的虚拟服务器。因为这种技术容易形成单点故障，从而造成网路无法访问，并且存在带宽瓶颈。所以LVS又提供了下面两种实现。
Virtual Server via IP Tunneling （VS/TUN ）： 通过IP隧道实现虚拟服务。
Virtual Server via Direct Routing （VS/DR） ：直接路由实现虚拟服务器的方法（负载能力最强），本文搭建的就是DR模式。
LVS
使用Keepalived做LVS时，真实服务器(Real-Server)需要为ipvsadm单独写脚本,Windows 需环回网络接口，ipvsadm 启用并工作后，keepalived才会接管控制ipvsadm。
脚本:
代码如下 #!/bin/bashVIP=192.168.2.130
/etc/rc.d/init.d/functions
case "$1" in
start)
ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP
/sbin/route add -host $VIP dev lo:0
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
sysctl -p >/dev/null 2>&1
echo "RealServer Start OK"
;;
stop)
ifconfig lo:0 down
route del $VIP >/dev/null 2>&1
echo "0" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "0" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "0" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "0" >/proc/sys/net/ipv4/conf/all/arp_announce
echo "RealServer Stoped"
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
exit 0
ipvsadm
ipvsadm -l
ipvsadm -ln
ipvsadm -lnc
vrrp_script 配置
代码如下vrrp_script chk_sshd {
script "killall -0 sshd" # cheaper than pidof
interval 2 # check every 2 seconds
weight -4 # default prio: -4 if KO
# weight -40 # if failed, decrease 40 of the priority
fall 1 # require 2 failures for failures
rise 1 # require 1 sucesses for ok
}
vrrp_script chk_haproxy {
script "killall -0 haproxy" # cheaper than pidof
interval 2 # check every 2 seconds
}
vrrp_script chk_http_port {
#script "/tcp/127.0.0.1/80" # connects and exits
#script "nc -z 127.0.0.1 80" # connects and exits
script "
interval 1 # check every second
weight -2 # default prio: -2 if connect fails
}
vrrp_script chk_https_port {
script "/tcp/127.0.0.1/443"
interval 1
weight -2
}
vrrp_script chk_smtp_port {
script "/tcp/127.0.0.1/25"
interval 1
weight -2
}
vrrp_instance VI_1 {
interface eth0
state MASTER
virtual_router_id 51
priority 100
virtual_ipaddress {
192.168.200.18/25
}
track_interface {
eth1 weight 2 # prio = +2 if UP
eth2 weight -2 # prio = -2 if DOWN
eth3 # no weight, fault if down
}
track_script {
chk_sshd # use default weight from the script
chk_haproxy weight 2 # +2 if process is present
chk_http_port
chk_https_port
chk_smtp_port
}
}
vrrp_instance VI_2 {
interface eth1
state MASTER
virtual_router_id 52
priority 100
virtual_ipaddress {
192.168.201.18/26
}
track_interface {
eth0 weight 2 # prio = +2 if UP
eth2 weight -2 # prio = -2 if DOWN
eth3 # no weight, fault if down
}
track_script {
chk_haproxy weight 2
chk_http_port
chk_https_port
chk_smtp_port
}
}
一例配置：
代码如下! Configuration File for keepalived
global_defs {
notification_email {
notify@aooshi.org
}
notification_email_from servername@aooshi.org
smtp_server 192.168.2.111
smtp_connect_timeout 30
router_id webcache253-keepalived
}
vrrp_script check_http {
script "
interval 5
weight -10
}
vrrp_instance VI_158 {
state BACKUP
interface eth0
virtual_router_id 62
priority 99
advert_int 1
smtp_alert
authentication {
auth_type PASS
auth_pass webcache
}
virtual_ipaddress {
192.168.2.158 brd 192.168.2.255 label eth0:158
}
track_script {
check_http
}
}
vrrp_instance VI_159 {
state MASTER
interface eth0
virtual_router_id 63
priority 100
advert_int 1
smtp_alert
authentication {
auth_type PASS
auth_pass webcache
}
virtual_ipaddress {
192.168.2.159 brd 192.168.2.255 label eth0:159
}
track_script {
check_http
}
}