Use ipvsadm + ldirectord in CentOS to implement high-availability clusters

There are four servers: 192.168.0.34, 192.168.0.35, 192.168.0.36, and 192.168.0.37.
192.168.0.37 is an e-mail service running on nas, 35, and 36.
A scheduler was created on port 37 to allocate services with ports 80, 25, and 110 to ports, 35, and 36.

Specific Configuration:
On server 37, an rpm package of ipvsadm is installed first.
Yum install ipvsadm # obtains the ipvsadm software, which is responsible for load balancing and requests to backend services.
And then the tutorial
Reference written by others. The direct routing mode is used.
#! /Bin/bash
VIP = 192.168.0.38
RIP1 = 192.168.0.34
RIP2 = 192.168.0.35
RIP3 = 192.168.0.36
GW = 192.168.0.33
# Clear IPVS table
/Sbin/ipvsadm-C
/Sbin/ifconfig eth0: 0 $ VIP broadcast $ VIP netmask 255.255.255.255 up
/Sbin/route add-host $ VIP dev eth0: 0
# Set LVS
/Sbin/ipvsadm-A-t $ VIP: 80-s rr
/Sbin/ipvsadm-a-t $ VIP: 80-r $ RIP1: 80-g
/Sbin/ipvsadm-a-t $ VIP: 80-r $ RIP2: 80-g
/Sbin/ipvsadm-a-t $ VIP: 80-r $ RIP3: 80-g
/Sbin/ipvsadm-A-t $ VIP: 25-s rr
/Sbin/ipvsadm-a-t $ VIP: 25-r $ RIP1: 25-g
/Sbin/ipvsadm-a-t $ VIP: 25-r $ RIP2: 25-g
/Sbin/ipvsadm-a-t $ VIP: 25-r $ RIP3: 25-g
/Sbin/ipvsadm-A-t $ VIP: 110-s rr
/Sbin/ipvsadm-a-t $ VIP: 110-r $ RIP1: 110-g
/Sbin/ipvsadm-a-t $ VIP: 110-r $ RIP2: 110-g
/Sbin/ipvsadm-a-t $ VIP: 110-r $ RIP3: 110-g
# Run LVS
/Sbin/ipvsadm
# End
The content is 192.168.0.38, which is the virtual address 192.168.0.34, 35, 36 is the real server. Load ports 80, 25, and 110.
34,35, 36 respectively/home/test. sh tutorial
#! /Bin/bash
VIP = 192.168.0.38
/Sbin/ifconfig lo: 0 $ VIP broadcast $ VIP netmask 255.255.255.255 up
/Sbin/route add-host $ VIP dev lo: 0
Echo 1>/proc/sys/net/ipv4/conf/all/arp_filter
Echo 1>/proc/sys/net/ipv4/conf/lo/arp_filter
Sysctl-p
# End
This script is used to filter arp packets, or edit/etc/sysctl. conf to modify system variables.
Net. ipv4.conf. lo. arp_ignore = 1
Net. ipv4.conf. lo. arp_announce = 2
Net. ipv4.ip _ forward = 1
Sysctl-p # configuration takes effect

Http://www.vergenet.net/linux/ldirectord/
Downloading lddirectord is a monitoring software.

You can download it in the following way 07 years ago and it is no longer valid.
{Cvs-d: pserver: guest@cvs.linux-ha.org:/home/cvs/linux-ha login
Cvs-z3-d: pserver: guest@cvs.linux-ha.org:/home/cvs/linux-ha co linux-ha /}

Current (20090906) Available Link
Http://hg.linux-ha.org/lha-2.1/archive/STABLE-2.1.4.tar.bz2


Then a configuration file is written.
Ldirectord. cf
Checktimeout = 3
Checkinterval = 1
# Fck = 127.0.0.1: 80 allback = 127.0.0.1: 80
Autoreload = yes
# Logfile = "/var/log/ldirectord. log"
# Logfile = "local0"
Quiescent = yes
# A sample virual with a fallback that will override the gobal setting
Virtual = 192.168.0.38: 80
Real = 192.168.0.34: 80 gate
Real = 192.168.0.35: 80 gate
Real = 192.168.0.36: 80 gate
Fallback = 127.0.0.1: 80
Service = http
Request = "test.html"
Receive = "Test Page"
Virtualhost = www.shiming.gov.cn
Scheduler = rr
Perpersistent = 600
Netmask = 255.255.255.255.255
Protocol = tcp
Virtual = 192.168.0.38: 25
Real = 192.168.0.34: 25 gate
Real = 192.168.0.35: 25 gate
Real = 192.168.0.36: 25 gate
Fallback = 127.0.0.1: 25
Service = smtp
Scheduler = rr
Perpersistent = 600
Protocol = tcp
Virtual = 192.168.0.38: 110
Real = 192.168.0.34: 110 gate
Real = 192.168.0.35: 110 gate
Real = 192.168.0.36: 110 gate
Fallback = 127.0.0.1: 110
Service = pop
Scheduler = rr
Login = "testemail"
Passwd = "emailtest"
Perpersistent = 600
Protocol = tcp

This is the result of monitoring.
Ldirectord/etc/ldirectord. cf start
Ldirectord/etc/ldirectord. cf stop
Tail-f/var/log/ldirectord. log. This is log

Check whether the lvs service is normal
Watch ipvsadm-l-n

Every 2.0 s: ipvsadm-l-n Sun Sep 6 19:39:51 2009

IP Virtual Server version 1.2.1 (size = 4096)
Prot LocalAddress: Port sched1_flags
-> RemoteAddress: Port Forward Weight ActiveConn InActConn
TCP 192.168.0.105: 80 rr
-> 192.168.0.104: 80 Route 1 0 0
-> 192.168.0.103: 80 Route 1 0 0
TCP 192.168.0.105: 3306 rr
-& Gt; 192.168.0.104: 3306 Route 1 0 0
-> 192.168.0.103: 3306 Route 1 0 0

Refer:
Http://bbs.chinaunix.net/viewthread.php? Tid = 1148139
Http://www.linuxvirtualserver.org/